ARM: tegra: power: Set minimum LP2 target residency
[linux-3.10.git] / fs / select.c
index b80e7eb..6b14dc7 100644 (file)
  *     of fds to overcome nfds < 16390 descriptors limit (Tigran Aivazian).
  */
 
+#include <linux/kernel.h>
+#include <linux/sched.h>
 #include <linux/syscalls.h>
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <linux/poll.h>
 #include <linux/personality.h> /* for STICKY_TIMEOUTS */
 #include <linux/file.h>
+#include <linux/fdtable.h>
 #include <linux/fs.h>
+#include <linux/rcupdate.h>
+#include <linux/hrtimer.h>
+#include <linux/sched/rt.h>
+#include <linux/freezer.h>
 
 #include <asm/uaccess.h>
 
-#define ROUND_UP(x,y) (((x)+(y)-1)/(y))
-#define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
 
-struct poll_table_entry {
-       struct file * filp;
-       wait_queue_t wait;
-       wait_queue_head_t * wait_address;
-};
+/*
+ * Estimate expected accuracy in ns from a timeval.
+ *
+ * After quite a bit of churning around, we've settled on
+ * a simple thing of taking 0.1% of the timeout as the
+ * slack, with a cap of 100 msec.
+ * "nice" tasks get a 0.5% slack instead.
+ *
+ * Consider this comment an open invitation to come up with even
+ * better solutions..
+ */
+
+#define MAX_SLACK      (100 * NSEC_PER_MSEC)
+
+static long __estimate_accuracy(struct timespec *tv)
+{
+       long slack;
+       int divfactor = 1000;
+
+       if (tv->tv_sec < 0)
+               return 0;
+
+       if (task_nice(current) > 0)
+               divfactor = divfactor / 5;
+
+       if (tv->tv_sec > MAX_SLACK / (NSEC_PER_SEC/divfactor))
+               return MAX_SLACK;
+
+       slack = tv->tv_nsec / divfactor;
+       slack += tv->tv_sec * (NSEC_PER_SEC/divfactor);
+
+       if (slack > MAX_SLACK)
+               return MAX_SLACK;
+
+       return slack;
+}
+
+long select_estimate_accuracy(struct timespec *tv)
+{
+       unsigned long ret;
+       struct timespec now;
+
+       /*
+        * Realtime tasks get a slack of 0 for obvious reasons.
+        */
+
+       if (rt_task(current))
+               return 0;
+
+       ktime_get_ts(&now);
+       now = timespec_sub(*tv, now);
+       ret = __estimate_accuracy(&now);
+       if (ret < current->timer_slack_ns)
+               return current->timer_slack_ns;
+       return ret;
+}
+
+
 
 struct poll_table_page {
        struct poll_table_page * next;
@@ -61,15 +118,26 @@ static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
 void poll_initwait(struct poll_wqueues *pwq)
 {
        init_poll_funcptr(&pwq->pt, __pollwait);
+       pwq->polling_task = current;
+       pwq->triggered = 0;
        pwq->error = 0;
        pwq->table = NULL;
+       pwq->inline_index = 0;
 }
-
 EXPORT_SYMBOL(poll_initwait);
 
+static void free_poll_entry(struct poll_table_entry *entry)
+{
+       remove_wait_queue(entry->wait_address, &entry->wait);
+       fput(entry->filp);
+}
+
 void poll_freewait(struct poll_wqueues *pwq)
 {
        struct poll_table_page * p = pwq->table;
+       int i;
+       for (i = 0; i < pwq->inline_index; i++)
+               free_poll_entry(pwq->inline_entries + i);
        while (p) {
                struct poll_table_entry * entry;
                struct poll_table_page *old;
@@ -77,31 +145,29 @@ void poll_freewait(struct poll_wqueues *pwq)
                entry = p->entry;
                do {
                        entry--;
-                       remove_wait_queue(entry->wait_address,&entry->wait);
-                       fput(entry->filp);
+                       free_poll_entry(entry);
                } while (entry > p->entries);
                old = p;
                p = p->next;
                free_page((unsigned long) old);
        }
 }
-
 EXPORT_SYMBOL(poll_freewait);
 
-static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
-                      poll_table *_p)
+static struct poll_table_entry *poll_get_entry(struct poll_wqueues *p)
 {
-       struct poll_wqueues *p = container_of(_p, struct poll_wqueues, pt);
        struct poll_table_page *table = p->table;
 
+       if (p->inline_index < N_INLINE_POLL_ENTRIES)
+               return p->inline_entries + p->inline_index++;
+
        if (!table || POLL_TABLE_FULL(table)) {
                struct poll_table_page *new_table;
 
                new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
                if (!new_table) {
                        p->error = -ENOMEM;
-                       __set_current_state(TASK_RUNNING);
-                       return;
+                       return NULL;
                }
                new_table->entry = new_table->entries;
                new_table->next = table;
@@ -109,16 +175,162 @@ static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
                table = new_table;
        }
 
-       /* Add a new entry */
-       {
-               struct poll_table_entry * entry = table->entry;
-               table->entry = entry+1;
-               get_file(filp);
-               entry->filp = filp;
-               entry->wait_address = wait_address;
-               init_waitqueue_entry(&entry->wait, current);
-               add_wait_queue(wait_address,&entry->wait);
+       return table->entry++;
+}
+
+static int __pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key)
+{
+       struct poll_wqueues *pwq = wait->private;
+       DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task);
+
+       /*
+        * Although this function is called under waitqueue lock, LOCK
+        * doesn't imply write barrier and the users expect write
+        * barrier semantics on wakeup functions.  The following
+        * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up()
+        * and is paired with set_mb() in poll_schedule_timeout.
+        */
+       smp_wmb();
+       pwq->triggered = 1;
+
+       /*
+        * Perform the default wake up operation using a dummy
+        * waitqueue.
+        *
+        * TODO: This is hacky but there currently is no interface to
+        * pass in @sync.  @sync is scheduled to be removed and once
+        * that happens, wake_up_process() can be used directly.
+        */
+       return default_wake_function(&dummy_wait, mode, sync, key);
+}
+
+static int pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key)
+{
+       struct poll_table_entry *entry;
+
+       entry = container_of(wait, struct poll_table_entry, wait);
+       if (key && !((unsigned long)key & entry->key))
+               return 0;
+       return __pollwake(wait, mode, sync, key);
+}
+
+/* Add a new entry */
+static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
+                               poll_table *p)
+{
+       struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt);
+       struct poll_table_entry *entry = poll_get_entry(pwq);
+       if (!entry)
+               return;
+       entry->filp = get_file(filp);
+       entry->wait_address = wait_address;
+       entry->key = p->_key;
+       init_waitqueue_func_entry(&entry->wait, pollwake);
+       entry->wait.private = pwq;
+       add_wait_queue(wait_address, &entry->wait);
+}
+
+int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
+                         ktime_t *expires, unsigned long slack)
+{
+       int rc = -EINTR;
+
+       set_current_state(state);
+       if (!pwq->triggered)
+               rc = freezable_schedule_hrtimeout_range(expires, slack,
+                                                       HRTIMER_MODE_ABS);
+       __set_current_state(TASK_RUNNING);
+
+       /*
+        * Prepare for the next iteration.
+        *
+        * The following set_mb() serves two purposes.  First, it's
+        * the counterpart rmb of the wmb in pollwake() such that data
+        * written before wake up is always visible after wake up.
+        * Second, the full barrier guarantees that triggered clearing
+        * doesn't pass event check of the next iteration.  Note that
+        * this problem doesn't exist for the first iteration as
+        * add_wait_queue() has full barrier semantics.
+        */
+       set_mb(pwq->triggered, 0);
+
+       return rc;
+}
+EXPORT_SYMBOL(poll_schedule_timeout);
+
+/**
+ * poll_select_set_timeout - helper function to setup the timeout value
+ * @to:                pointer to timespec variable for the final timeout
+ * @sec:       seconds (from user space)
+ * @nsec:      nanoseconds (from user space)
+ *
+ * Note, we do not use a timespec for the user space value here, That
+ * way we can use the function for timeval and compat interfaces as well.
+ *
+ * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0.
+ */
+int poll_select_set_timeout(struct timespec *to, long sec, long nsec)
+{
+       struct timespec ts = {.tv_sec = sec, .tv_nsec = nsec};
+
+       if (!timespec_valid(&ts))
+               return -EINVAL;
+
+       /* Optimize for the zero timeout value here */
+       if (!sec && !nsec) {
+               to->tv_sec = to->tv_nsec = 0;
+       } else {
+               ktime_get_ts(to);
+               *to = timespec_add_safe(*to, ts);
        }
+       return 0;
+}
+
+static int poll_select_copy_remaining(struct timespec *end_time, void __user *p,
+                                     int timeval, int ret)
+{
+       struct timespec rts;
+       struct timeval rtv;
+
+       if (!p)
+               return ret;
+
+       if (current->personality & STICKY_TIMEOUTS)
+               goto sticky;
+
+       /* No update for zero timeout */
+       if (!end_time->tv_sec && !end_time->tv_nsec)
+               return ret;
+
+       ktime_get_ts(&rts);
+       rts = timespec_sub(*end_time, rts);
+       if (rts.tv_sec < 0)
+               rts.tv_sec = rts.tv_nsec = 0;
+
+       if (timeval) {
+               if (sizeof(rtv) > sizeof(rtv.tv_sec) + sizeof(rtv.tv_usec))
+                       memset(&rtv, 0, sizeof(rtv));
+               rtv.tv_sec = rts.tv_sec;
+               rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC;
+
+               if (!copy_to_user(p, &rtv, sizeof(rtv)))
+                       return ret;
+
+       } else if (!copy_to_user(p, &rts, sizeof(rts)))
+               return ret;
+
+       /*
+        * If an application puts its timeval in read-only memory, we
+        * don't want the Linux-specific update to the timeval to
+        * cause a fault after the select has completed
+        * successfully. However, because we're not updating the
+        * timeval, we can't restart the system call.
+        */
+
+sticky:
+       if (ret == -ERESTARTNOHAND)
+               ret = -EINTR;
+       return ret;
 }
 
 #define FDS_IN(fds, n)         (fds->in + n)
@@ -132,11 +344,13 @@ static int max_select_fd(unsigned long n, fd_set_bits *fds)
        unsigned long *open_fds;
        unsigned long set;
        int max;
+       struct fdtable *fdt;
 
        /* handle last in-complete long-word first */
-       set = ~(~0UL << (n & (__NFDBITS-1)));
-       n /= __NFDBITS;
-       open_fds = current->files->open_fds->fds_bits+n;
+       set = ~(~0UL << (n & (BITS_PER_LONG-1)));
+       n /= BITS_PER_LONG;
+       fdt = files_fdtable(current->files);
+       open_fds = fdt->open_fds + n;
        max = 0;
        if (set) {
                set &= BITS(fds, n);
@@ -161,31 +375,37 @@ get_max:
                        max++;
                        set >>= 1;
                } while (set);
-               max += n * __NFDBITS;
+               max += n * BITS_PER_LONG;
        }
 
        return max;
 }
 
-#define BIT(i)         (1UL << ((i)&(__NFDBITS-1)))
-#define MEM(i,m)       ((m)+(unsigned)(i)/__NFDBITS)
-#define ISSET(i,m)     (((i)&*(m)) != 0)
-#define SET(i,m)       (*(m) |= (i))
-
 #define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR)
 #define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
 #define POLLEX_SET (POLLPRI)
 
-int do_select(int n, fd_set_bits *fds, long *timeout)
+static inline void wait_key_set(poll_table *wait, unsigned long in,
+                               unsigned long out, unsigned long bit)
 {
+       wait->_key = POLLEX_SET;
+       if (in & bit)
+               wait->_key |= POLLIN_SET;
+       if (out & bit)
+               wait->_key |= POLLOUT_SET;
+}
+
+int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
+{
+       ktime_t expire, *to = NULL;
        struct poll_wqueues table;
        poll_table *wait;
-       int retval, i;
-       long __timeout = *timeout;
+       int retval, i, timed_out = 0;
+       unsigned long slack = 0;
 
-       spin_lock(&current->files->file_lock);
+       rcu_read_lock();
        retval = max_select_fd(n, fds);
-       spin_unlock(&current->files->file_lock);
+       rcu_read_unlock();
 
        if (retval < 0)
                return retval;
@@ -193,56 +413,64 @@ int do_select(int n, fd_set_bits *fds, long *timeout)
 
        poll_initwait(&table);
        wait = &table.pt;
-       if (!__timeout)
-               wait = NULL;
+       if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
+               wait->_qproc = NULL;
+               timed_out = 1;
+       }
+
+       if (end_time && !timed_out)
+               slack = select_estimate_accuracy(end_time);
+
        retval = 0;
        for (;;) {
                unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
 
-               set_current_state(TASK_INTERRUPTIBLE);
-
                inp = fds->in; outp = fds->out; exp = fds->ex;
                rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;
 
                for (i = 0; i < n; ++rinp, ++routp, ++rexp) {
                        unsigned long in, out, ex, all_bits, bit = 1, mask, j;
                        unsigned long res_in = 0, res_out = 0, res_ex = 0;
-                       struct file_operations *f_op = NULL;
-                       struct file *file = NULL;
 
                        in = *inp++; out = *outp++; ex = *exp++;
                        all_bits = in | out | ex;
                        if (all_bits == 0) {
-                               i += __NFDBITS;
+                               i += BITS_PER_LONG;
                                continue;
                        }
 
-                       for (j = 0; j < __NFDBITS; ++j, ++i, bit <<= 1) {
+                       for (j = 0; j < BITS_PER_LONG; ++j, ++i, bit <<= 1) {
+                               struct fd f;
                                if (i >= n)
                                        break;
                                if (!(bit & all_bits))
                                        continue;
-                               file = fget(i);
-                               if (file) {
-                                       f_op = file->f_op;
+                               f = fdget(i);
+                               if (f.file) {
+                                       const struct file_operations *f_op;
+                                       f_op = f.file->f_op;
                                        mask = DEFAULT_POLLMASK;
-                                       if (f_op && f_op->poll)
-                                               mask = (*f_op->poll)(file, retval ? NULL : wait);
-                                       fput(file);
+                                       if (f_op && f_op->poll) {
+                                               wait_key_set(wait, in, out, bit);
+                                               mask = (*f_op->poll)(f.file, wait);
+                                       }
+                                       fdput(f);
                                        if ((mask & POLLIN_SET) && (in & bit)) {
                                                res_in |= bit;
                                                retval++;
+                                               wait->_qproc = NULL;
                                        }
                                        if ((mask & POLLOUT_SET) && (out & bit)) {
                                                res_out |= bit;
                                                retval++;
+                                               wait->_qproc = NULL;
                                        }
                                        if ((mask & POLLEX_SET) && (ex & bit)) {
                                                res_ex |= bit;
                                                retval++;
+                                               wait->_qproc = NULL;
                                        }
                                }
-                               cond_resched();
                        }
                        if (res_in)
                                *rinp = res_in;
@@ -250,37 +478,36 @@ int do_select(int n, fd_set_bits *fds, long *timeout)
                                *routp = res_out;
                        if (res_ex)
                                *rexp = res_ex;
+                       cond_resched();
                }
-               wait = NULL;
-               if (retval || !__timeout || signal_pending(current))
+               wait->_qproc = NULL;
+               if (retval || timed_out || signal_pending(current))
                        break;
-               if(table.error) {
+               if (table.error) {
                        retval = table.error;
                        break;
                }
-               __timeout = schedule_timeout(__timeout);
+
+               /*
+                * If this is the first loop and we have a timeout
+                * given, then we convert to ktime_t and set the to
+                * pointer to the expiry value.
+                */
+               if (end_time && !to) {
+                       expire = timespec_to_ktime(*end_time);
+                       to = &expire;
+               }
+
+               if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE,
+                                          to, slack))
+                       timed_out = 1;
        }
-       __set_current_state(TASK_RUNNING);
 
        poll_freewait(&table);
 
-       /*
-        * Up-to-date the caller timeout.
-        */
-       *timeout = __timeout;
        return retval;
 }
 
-static void *select_bits_alloc(int size)
-{
-       return kmalloc(6 * size, GFP_KERNEL);
-}
-
-static void select_bits_free(void *bits, int size)
-{
-       kfree(bits);
-}
-
 /*
  * We can actually return ERESTARTSYS instead of EINTR, but I'd
  * like to be certain this leads to no problems. So I return
@@ -289,63 +516,49 @@ static void select_bits_free(void *bits, int size)
  * Update: ERESTARTSYS breaks at least the xview clock binary, so
  * I'm trying ERESTARTNOHAND which restart only when you want to.
  */
-#define MAX_SELECT_SECONDS \
-       ((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)
-
-asmlinkage long
-sys_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp, struct timeval __user *tvp)
+int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
+                          fd_set __user *exp, struct timespec *end_time)
 {
        fd_set_bits fds;
-       char *bits;
-       long timeout;
-       int ret, size, max_fdset;
-
-       timeout = MAX_SCHEDULE_TIMEOUT;
-       if (tvp) {
-               time_t sec, usec;
-
-               if (!access_ok(VERIFY_READ, tvp, sizeof(*tvp))
-                   || __get_user(sec, &tvp->tv_sec)
-                   || __get_user(usec, &tvp->tv_usec)) {
-                       ret = -EFAULT;
-                       goto out_nofds;
-               }
-
-               ret = -EINVAL;
-               if (sec < 0 || usec < 0)
-                       goto out_nofds;
-
-               if ((unsigned long) sec < MAX_SELECT_SECONDS) {
-                       timeout = ROUND_UP(usec, 1000000/HZ);
-                       timeout += sec * (unsigned long) HZ;
-               }
-       }
+       void *bits;
+       int ret, max_fds;
+       unsigned int size;
+       struct fdtable *fdt;
+       /* Allocate small arguments on the stack to save memory and be faster */
+       long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];
 
        ret = -EINVAL;
        if (n < 0)
                goto out_nofds;
 
-       /* max_fdset can increase, so grab it once to avoid race */
-       max_fdset = current->files->max_fdset;
-       if (n > max_fdset)
-               n = max_fdset;
+       /* max_fds can increase, so grab it once to avoid race */
+       rcu_read_lock();
+       fdt = files_fdtable(current->files);
+       max_fds = fdt->max_fds;
+       rcu_read_unlock();
+       if (n > max_fds)
+               n = max_fds;
 
        /*
         * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
         * since we used fdset we need to allocate memory in units of
         * long-words. 
         */
-       ret = -ENOMEM;
        size = FDS_BYTES(n);
-       bits = select_bits_alloc(size);
-       if (!bits)
-               goto out_nofds;
-       fds.in      = (unsigned long *)  bits;
-       fds.out     = (unsigned long *) (bits +   size);
-       fds.ex      = (unsigned long *) (bits + 2*size);
-       fds.res_in  = (unsigned long *) (bits + 3*size);
-       fds.res_out = (unsigned long *) (bits + 4*size);
-       fds.res_ex  = (unsigned long *) (bits + 5*size);
+       bits = stack_fds;
+       if (size > sizeof(stack_fds) / 6) {
+               /* Not enough space in on-stack array; must use kmalloc */
+               ret = -ENOMEM;
+               bits = kmalloc(6 * size, GFP_KERNEL);
+               if (!bits)
+                       goto out_nofds;
+       }
+       fds.in      = bits;
+       fds.out     = bits +   size;
+       fds.ex      = bits + 2*size;
+       fds.res_in  = bits + 3*size;
+       fds.res_out = bits + 4*size;
+       fds.res_ex  = bits + 5*size;
 
        if ((ret = get_fd_set(n, inp, fds.in)) ||
            (ret = get_fd_set(n, outp, fds.out)) ||
@@ -355,18 +568,7 @@ sys_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp, s
        zero_fd_set(n, fds.res_out);
        zero_fd_set(n, fds.res_ex);
 
-       ret = do_select(n, &fds, &timeout);
-
-       if (tvp && !(current->personality & STICKY_TIMEOUTS)) {
-               time_t sec = 0, usec = 0;
-               if (timeout) {
-                       sec = timeout / HZ;
-                       usec = timeout % HZ;
-                       usec *= (1000000/HZ);
-               }
-               put_user(sec, &tvp->tv_sec);
-               put_user(usec, &tvp->tv_usec);
-       }
+       ret = do_select(n, &fds, end_time);
 
        if (ret < 0)
                goto out;
@@ -383,11 +585,125 @@ sys_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp, s
                ret = -EFAULT;
 
 out:
-       select_bits_free(bits, size);
+       if (bits != stack_fds)
+               kfree(bits);
 out_nofds:
        return ret;
 }
 
+SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,
+               fd_set __user *, exp, struct timeval __user *, tvp)
+{
+       struct timespec end_time, *to = NULL;
+       struct timeval tv;
+       int ret;
+
+       if (tvp) {
+               if (copy_from_user(&tv, tvp, sizeof(tv)))
+                       return -EFAULT;
+
+               to = &end_time;
+               if (poll_select_set_timeout(to,
+                               tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),
+                               (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))
+                       return -EINVAL;
+       }
+
+       ret = core_sys_select(n, inp, outp, exp, to);
+       ret = poll_select_copy_remaining(&end_time, tvp, 1, ret);
+
+       return ret;
+}
+
+static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp,
+                      fd_set __user *exp, struct timespec __user *tsp,
+                      const sigset_t __user *sigmask, size_t sigsetsize)
+{
+       sigset_t ksigmask, sigsaved;
+       struct timespec ts, end_time, *to = NULL;
+       int ret;
+
+       if (tsp) {
+               if (copy_from_user(&ts, tsp, sizeof(ts)))
+                       return -EFAULT;
+
+               to = &end_time;
+               if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
+                       return -EINVAL;
+       }
+
+       if (sigmask) {
+               /* XXX: Don't preclude handling different sized sigset_t's.  */
+               if (sigsetsize != sizeof(sigset_t))
+                       return -EINVAL;
+               if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
+                       return -EFAULT;
+
+               sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
+               sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+       }
+
+       ret = core_sys_select(n, inp, outp, exp, to);
+       ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
+
+       if (ret == -ERESTARTNOHAND) {
+               /*
+                * Don't restore the signal mask yet. Let do_signal() deliver
+                * the signal on the way back to userspace, before the signal
+                * mask is restored.
+                */
+               if (sigmask) {
+                       memcpy(&current->saved_sigmask, &sigsaved,
+                                       sizeof(sigsaved));
+                       set_restore_sigmask();
+               }
+       } else if (sigmask)
+               sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+
+       return ret;
+}
+
+/*
+ * Most architectures can't handle 7-argument syscalls. So we provide a
+ * 6-argument version where the sixth argument is a pointer to a structure
+ * which has a pointer to the sigset_t itself followed by a size_t containing
+ * the sigset size.
+ */
+SYSCALL_DEFINE6(pselect6, int, n, fd_set __user *, inp, fd_set __user *, outp,
+               fd_set __user *, exp, struct timespec __user *, tsp,
+               void __user *, sig)
+{
+       size_t sigsetsize = 0;
+       sigset_t __user *up = NULL;
+
+       if (sig) {
+               if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t))
+                   || __get_user(up, (sigset_t __user * __user *)sig)
+                   || __get_user(sigsetsize,
+                               (size_t __user *)(sig+sizeof(void *))))
+                       return -EFAULT;
+       }
+
+       return do_pselect(n, inp, outp, exp, tsp, up, sigsetsize);
+}
+
+#ifdef __ARCH_WANT_SYS_OLD_SELECT
+struct sel_arg_struct {
+       unsigned long n;
+       fd_set __user *inp, *outp, *exp;
+       struct timeval __user *tvp;
+};
+
+SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg)
+{
+       struct sel_arg_struct a;
+
+       if (copy_from_user(&a, arg, sizeof(a)))
+               return -EFAULT;
+       return sys_select(a.n, a.inp, a.outp, a.exp, a.tvp);
+}
+#endif
+
 struct poll_list {
        struct poll_list *next;
        int len;
@@ -396,141 +712,278 @@ struct poll_list {
 
 #define POLLFD_PER_PAGE  ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
 
-static void do_pollfd(unsigned int num, struct pollfd * fdpage,
-       poll_table ** pwait, int *count)
+/*
+ * Fish for pollable events on the pollfd->fd file descriptor. We're only
+ * interested in events matching the pollfd->events mask, and the result
+ * matching that mask is both recorded in pollfd->revents and returned. The
+ * pwait poll_table will be used by the fd-provided poll handler for waiting,
+ * if pwait->_qproc is non-NULL.
+ */
+static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait)
 {
-       int i;
-
-       for (i = 0; i < num; i++) {
-               int fd;
-               unsigned int mask;
-               struct pollfd *fdp;
-
-               mask = 0;
-               fdp = fdpage+i;
-               fd = fdp->fd;
-               if (fd >= 0) {
-                       struct file * file = fget(fd);
-                       mask = POLLNVAL;
-                       if (file != NULL) {
-                               mask = DEFAULT_POLLMASK;
-                               if (file->f_op && file->f_op->poll)
-                                       mask = file->f_op->poll(file, *pwait);
-                               mask &= fdp->events | POLLERR | POLLHUP;
-                               fput(file);
-                       }
-                       if (mask) {
-                               *pwait = NULL;
-                               (*count)++;
+       unsigned int mask;
+       int fd;
+
+       mask = 0;
+       fd = pollfd->fd;
+       if (fd >= 0) {
+               struct fd f = fdget(fd);
+               mask = POLLNVAL;
+               if (f.file) {
+                       mask = DEFAULT_POLLMASK;
+                       if (f.file->f_op && f.file->f_op->poll) {
+                               pwait->_key = pollfd->events|POLLERR|POLLHUP;
+                               mask = f.file->f_op->poll(f.file, pwait);
                        }
+                       /* Mask out unneeded events. */
+                       mask &= pollfd->events | POLLERR | POLLHUP;
+                       fdput(f);
                }
-               fdp->revents = mask;
        }
+       pollfd->revents = mask;
+
+       return mask;
 }
 
 static int do_poll(unsigned int nfds,  struct poll_list *list,
-                       struct poll_wqueues *wait, long timeout)
+                  struct poll_wqueues *wait, struct timespec *end_time)
 {
-       int count = 0;
        poll_table* pt = &wait->pt;
+       ktime_t expire, *to = NULL;
+       int timed_out = 0, count = 0;
+       unsigned long slack = 0;
+
+       /* Optimise the no-wait case */
+       if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
+               pt->_qproc = NULL;
+               timed_out = 1;
+       }
+
+       if (end_time && !timed_out)
+               slack = select_estimate_accuracy(end_time);
 
-       if (!timeout)
-               pt = NULL;
        for (;;) {
                struct poll_list *walk;
-               set_current_state(TASK_INTERRUPTIBLE);
-               walk = list;
-               while(walk != NULL) {
-                       do_pollfd( walk->len, walk->entries, &pt, &count);
-                       walk = walk->next;
+
+               for (walk = list; walk != NULL; walk = walk->next) {
+                       struct pollfd * pfd, * pfd_end;
+
+                       pfd = walk->entries;
+                       pfd_end = pfd + walk->len;
+                       for (; pfd != pfd_end; pfd++) {
+                               /*
+                                * Fish for events. If we found one, record it
+                                * and kill poll_table->_qproc, so we don't
+                                * needlessly register any other waiters after
+                                * this. They'll get immediately deregistered
+                                * when we break out and return.
+                                */
+                               if (do_pollfd(pfd, pt)) {
+                                       count++;
+                                       pt->_qproc = NULL;
+                               }
+                       }
                }
-               pt = NULL;
-               if (count || !timeout || signal_pending(current))
-                       break;
-               count = wait->error;
-               if (count)
+               /*
+                * All waiters have already been registered, so don't provide
+                * a poll_table->_qproc to them on the next loop iteration.
+                */
+               pt->_qproc = NULL;
+               if (!count) {
+                       count = wait->error;
+                       if (signal_pending(current))
+                               count = -EINTR;
+               }
+               if (count || timed_out)
                        break;
-               timeout = schedule_timeout(timeout);
+
+               /*
+                * If this is the first loop and we have a timeout
+                * given, then we convert to ktime_t and set the to
+                * pointer to the expiry value.
+                */
+               if (end_time && !to) {
+                       expire = timespec_to_ktime(*end_time);
+                       to = &expire;
+               }
+
+               if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack))
+                       timed_out = 1;
        }
-       __set_current_state(TASK_RUNNING);
        return count;
 }
 
-asmlinkage long sys_poll(struct pollfd __user * ufds, unsigned int nfds, long timeout)
+#define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list))  / \
+                       sizeof(struct pollfd))
+
+int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
+               struct timespec *end_time)
 {
        struct poll_wqueues table;
-       int fdcount, err;
-       unsigned int i;
-       struct poll_list *head;
-       struct poll_list *walk;
-
-       /* Do a sanity check on nfds ... */
-       if (nfds > current->files->max_fdset && nfds > OPEN_MAX)
+       int err = -EFAULT, fdcount, len, size;
+       /* Allocate small arguments on the stack to save memory and be
+          faster - use long to make sure the buffer is aligned properly
+          on 64 bit archs to avoid unaligned access */
+       long stack_pps[POLL_STACK_ALLOC/sizeof(long)];
+       struct poll_list *const head = (struct poll_list *)stack_pps;
+       struct poll_list *walk = head;
+       unsigned long todo = nfds;
+
+       if (nfds > rlimit(RLIMIT_NOFILE))
                return -EINVAL;
 
-       if (timeout) {
-               /* Careful about overflow in the intermediate values */
-               if ((unsigned long) timeout < MAX_SCHEDULE_TIMEOUT / HZ)
-                       timeout = (unsigned long)(timeout*HZ+999)/1000+1;
-               else /* Negative or overflow */
-                       timeout = MAX_SCHEDULE_TIMEOUT;
-       }
-
-       poll_initwait(&table);
+       len = min_t(unsigned int, nfds, N_STACK_PPS);
+       for (;;) {
+               walk->next = NULL;
+               walk->len = len;
+               if (!len)
+                       break;
 
-       head = NULL;
-       walk = NULL;
-       i = nfds;
-       err = -ENOMEM;
-       while(i!=0) {
-               struct poll_list *pp;
-               pp = kmalloc(sizeof(struct poll_list)+
-                               sizeof(struct pollfd)*
-                               (i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i),
-                                       GFP_KERNEL);
-               if(pp==NULL)
+               if (copy_from_user(walk->entries, ufds + nfds-todo,
+                                       sizeof(struct pollfd) * walk->len))
                        goto out_fds;
-               pp->next=NULL;
-               pp->len = (i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i);
-               if (head == NULL)
-                       head = pp;
-               else
-                       walk->next = pp;
-
-               walk = pp;
-               if (copy_from_user(pp->entries, ufds + nfds-i, 
-                               sizeof(struct pollfd)*pp->len)) {
-                       err = -EFAULT;
+
+               todo -= walk->len;
+               if (!todo)
+                       break;
+
+               len = min(todo, POLLFD_PER_PAGE);
+               size = sizeof(struct poll_list) + sizeof(struct pollfd) * len;
+               walk = walk->next = kmalloc(size, GFP_KERNEL);
+               if (!walk) {
+                       err = -ENOMEM;
                        goto out_fds;
                }
-               i -= pp->len;
        }
-       fdcount = do_poll(nfds, head, &table, timeout);
 
-       /* OK, now copy the revents fields back to user space. */
-       walk = head;
-       err = -EFAULT;
-       while(walk != NULL) {
+       poll_initwait(&table);
+       fdcount = do_poll(nfds, head, &table, end_time);
+       poll_freewait(&table);
+
+       for (walk = head; walk; walk = walk->next) {
                struct pollfd *fds = walk->entries;
                int j;
 
-               for (j=0; j < walk->len; j++, ufds++) {
-                       if(__put_user(fds[j].revents, &ufds->revents))
+               for (j = 0; j < walk->len; j++, ufds++)
+                       if (__put_user(fds[j].revents, &ufds->revents))
                                goto out_fds;
-               }
-               walk = walk->next;
        }
+
        err = fdcount;
-       if (!fdcount && signal_pending(current))
-               err = -EINTR;
 out_fds:
-       walk = head;
-       while(walk!=NULL) {
-               struct poll_list *pp = walk->next;
-               kfree(walk);
-               walk = pp;
+       walk = head->next;
+       while (walk) {
+               struct poll_list *pos = walk;
+               walk = walk->next;
+               kfree(pos);
        }
-       poll_freewait(&table);
+
        return err;
 }
+
+static long do_restart_poll(struct restart_block *restart_block)
+{
+       struct pollfd __user *ufds = restart_block->poll.ufds;
+       int nfds = restart_block->poll.nfds;
+       struct timespec *to = NULL, end_time;
+       int ret;
+
+       if (restart_block->poll.has_timeout) {
+               end_time.tv_sec = restart_block->poll.tv_sec;
+               end_time.tv_nsec = restart_block->poll.tv_nsec;
+               to = &end_time;
+       }
+
+       ret = do_sys_poll(ufds, nfds, to);
+
+       if (ret == -EINTR) {
+               restart_block->fn = do_restart_poll;
+               ret = -ERESTART_RESTARTBLOCK;
+       }
+       return ret;
+}
+
+SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,
+               int, timeout_msecs)
+{
+       struct timespec end_time, *to = NULL;
+       int ret;
+
+       if (timeout_msecs >= 0) {
+               to = &end_time;
+               poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC,
+                       NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC));
+       }
+
+       ret = do_sys_poll(ufds, nfds, to);
+
+       if (ret == -EINTR) {
+               struct restart_block *restart_block;
+
+               restart_block = &current_thread_info()->restart_block;
+               restart_block->fn = do_restart_poll;
+               restart_block->poll.ufds = ufds;
+               restart_block->poll.nfds = nfds;
+
+               if (timeout_msecs >= 0) {
+                       restart_block->poll.tv_sec = end_time.tv_sec;
+                       restart_block->poll.tv_nsec = end_time.tv_nsec;
+                       restart_block->poll.has_timeout = 1;
+               } else
+                       restart_block->poll.has_timeout = 0;
+
+               ret = -ERESTART_RESTARTBLOCK;
+       }
+       return ret;
+}
+
+SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds,
+               struct timespec __user *, tsp, const sigset_t __user *, sigmask,
+               size_t, sigsetsize)
+{
+       sigset_t ksigmask, sigsaved;
+       struct timespec ts, end_time, *to = NULL;
+       int ret;
+
+       if (tsp) {
+               if (copy_from_user(&ts, tsp, sizeof(ts)))
+                       return -EFAULT;
+
+               to = &end_time;
+               if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
+                       return -EINVAL;
+       }
+
+       if (sigmask) {
+               /* XXX: Don't preclude handling different sized sigset_t's.  */
+               if (sigsetsize != sizeof(sigset_t))
+                       return -EINVAL;
+               if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
+                       return -EFAULT;
+
+               sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
+               sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+       }
+
+       ret = do_sys_poll(ufds, nfds, to);
+
+       /* We can restart this syscall, usually */
+       if (ret == -EINTR) {
+               /*
+                * Don't restore the signal mask yet. Let do_signal() deliver
+                * the signal on the way back to userspace, before the signal
+                * mask is restored.
+                */
+               if (sigmask) {
+                       memcpy(&current->saved_sigmask, &sigsaved,
+                                       sizeof(sigsaved));
+                       set_restore_sigmask();
+               }
+               ret = -ERESTARTNOHAND;
+       } else if (sigmask)
+               sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+
+       ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
+
+       return ret;
+}