ocfs2: Don't repeat ocfs2_xattr_block_find()
[linux-2.6.git] / fs / select.c
index 47f4792..87df51e 100644 (file)
 #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 <asm/uaccess.h>
 
+
+/*
+ * 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..
+ */
+
+static long __estimate_accuracy(struct timespec *tv)
+{
+       long slack;
+       int divfactor = 1000;
+
+       if (task_nice(current) > 0)
+               divfactor = divfactor / 5;
+
+       slack = tv->tv_nsec / divfactor;
+       slack += tv->tv_sec * (NSEC_PER_SEC/divfactor);
+
+       if (slack > 100 * NSEC_PER_MSEC)
+               slack =  100 * NSEC_PER_MSEC;
+
+       if (slack < 0)
+               slack = 0;
+       return slack;
+}
+
+static long 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;
        struct poll_table_entry * entry;
@@ -129,6 +185,79 @@ static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
        add_wait_queue(wait_address, &entry->wait);
 }
 
+/**
+ * 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) {
+               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)
 #define FDS_OUT(fds, n)                (fds->out + n)
 #define FDS_EX(fds, n)         (fds->ex + n)
@@ -181,11 +310,13 @@ get_max:
 #define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
 #define POLLEX_SET (POLLPRI)
 
-int do_select(int n, fd_set_bits *fds, s64 *timeout)
+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;
+       int retval, i, timed_out = 0;
+       unsigned long slack = 0;
 
        rcu_read_lock();
        retval = max_select_fd(n, fds);
@@ -197,12 +328,17 @@ int do_select(int n, fd_set_bits *fds, s64 *timeout)
 
        poll_initwait(&table);
        wait = &table.pt;
-       if (!*timeout)
+       if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
                wait = NULL;
+               timed_out = 1;
+       }
+
+       if (end_time && !timed_out)
+               slack = estimate_accuracy(end_time);
+
        retval = 0;
        for (;;) {
                unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
-               long __timeout;
 
                set_current_state(TASK_INTERRUPTIBLE);
 
@@ -248,7 +384,6 @@ int do_select(int n, fd_set_bits *fds, s64 *timeout)
                                                retval++;
                                        }
                                }
-                               cond_resched();
                        }
                        if (res_in)
                                *rinp = res_in;
@@ -256,29 +391,28 @@ int do_select(int n, fd_set_bits *fds, s64 *timeout)
                                *routp = res_out;
                        if (res_ex)
                                *rexp = res_ex;
+                       cond_resched();
                }
                wait = NULL;
-               if (retval || !*timeout || signal_pending(current))
+               if (retval || timed_out || signal_pending(current))
                        break;
-               if(table.error) {
+               if (table.error) {
                        retval = table.error;
                        break;
                }
 
-               if (*timeout < 0) {
-                       /* Wait indefinitely */
-                       __timeout = MAX_SCHEDULE_TIMEOUT;
-               } else if (unlikely(*timeout >= (s64)MAX_SCHEDULE_TIMEOUT - 1)) {
-                       /* Wait for longer than MAX_SCHEDULE_TIMEOUT. Do it in a loop */
-                       __timeout = MAX_SCHEDULE_TIMEOUT - 1;
-                       *timeout -= __timeout;
-               } else {
-                       __timeout = *timeout;
-                       *timeout = 0;
+               /*
+                * 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;
                }
-               __timeout = schedule_timeout(__timeout);
-               if (*timeout >= 0)
-                       *timeout += __timeout;
+
+               if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS))
+                       timed_out = 1;
        }
        __set_current_state(TASK_RUNNING);
 
@@ -298,8 +432,8 @@ int do_select(int n, fd_set_bits *fds, s64 *timeout)
 #define MAX_SELECT_SECONDS \
        ((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)
 
-static int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
-                          fd_set __user *exp, s64 *timeout)
+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;
        void *bits;
@@ -350,7 +484,7 @@ static int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
        zero_fd_set(n, fds.res_out);
        zero_fd_set(n, fds.res_ex);
 
-       ret = do_select(n, &fds, timeout);
+       ret = do_select(n, &fds, end_time);
 
        if (ret < 0)
                goto out;
@@ -376,7 +510,7 @@ out_nofds:
 asmlinkage long sys_select(int n, fd_set __user *inp, fd_set __user *outp,
                        fd_set __user *exp, struct timeval __user *tvp)
 {
-       s64 timeout = -1;
+       struct timespec end_time, *to = NULL;
        struct timeval tv;
        int ret;
 
@@ -384,71 +518,35 @@ asmlinkage long sys_select(int n, fd_set __user *inp, fd_set __user *outp,
                if (copy_from_user(&tv, tvp, sizeof(tv)))
                        return -EFAULT;
 
-               if (tv.tv_sec < 0 || tv.tv_usec < 0)
+               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;
-
-               /* Cast to u64 to make GCC stop complaining */
-               if ((u64)tv.tv_sec >= (u64)MAX_INT64_SECONDS)
-                       timeout = -1;   /* infinite */
-               else {
-                       timeout = DIV_ROUND_UP(tv.tv_usec, USEC_PER_SEC/HZ);
-                       timeout += tv.tv_sec * HZ;
-               }
        }
 
-       ret = core_sys_select(n, inp, outp, exp, &timeout);
-
-       if (tvp) {
-               struct timeval rtv;
-
-               if (current->personality & STICKY_TIMEOUTS)
-                       goto sticky;
-               rtv.tv_usec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ));
-               rtv.tv_sec = timeout;
-               if (timeval_compare(&rtv, &tv) >= 0)
-                       rtv = tv;
-               if (copy_to_user(tvp, &rtv, sizeof(rtv))) {
-sticky:
-                       /*
-                        * 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.
-                        */
-                       if (ret == -ERESTARTNOHAND)
-                               ret = -EINTR;
-               }
-       }
+       ret = core_sys_select(n, inp, outp, exp, to);
+       ret = poll_select_copy_remaining(&end_time, tvp, 1, ret);
 
        return ret;
 }
 
-#ifdef TIF_RESTORE_SIGMASK
+#ifdef HAVE_SET_RESTORE_SIGMASK
 asmlinkage long sys_pselect7(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)
 {
-       s64 timeout = MAX_SCHEDULE_TIMEOUT;
        sigset_t ksigmask, sigsaved;
-       struct timespec ts;
+       struct timespec ts, end_time, *to = NULL;
        int ret;
 
        if (tsp) {
                if (copy_from_user(&ts, tsp, sizeof(ts)))
                        return -EFAULT;
 
-               if (ts.tv_sec < 0 || ts.tv_nsec < 0)
+               to = &end_time;
+               if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
                        return -EINVAL;
-
-               /* Cast to u64 to make GCC stop complaining */
-               if ((u64)ts.tv_sec >= (u64)MAX_INT64_SECONDS)
-                       timeout = -1;   /* infinite */
-               else {
-                       timeout = DIV_ROUND_UP(ts.tv_nsec, NSEC_PER_SEC/HZ);
-                       timeout += ts.tv_sec * HZ;
-               }
        }
 
        if (sigmask) {
@@ -462,32 +560,8 @@ asmlinkage long sys_pselect7(int n, fd_set __user *inp, fd_set __user *outp,
                sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
        }
 
-       ret = core_sys_select(n, inp, outp, exp, &timeout);
-
-       if (tsp) {
-               struct timespec rts;
-
-               if (current->personality & STICKY_TIMEOUTS)
-                       goto sticky;
-               rts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) *
-                                               1000;
-               rts.tv_sec = timeout;
-               if (timespec_compare(&rts, &ts) >= 0)
-                       rts = ts;
-               if (copy_to_user(tsp, &rts, sizeof(rts))) {
-sticky:
-                       /*
-                        * 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.
-                        */
-                       if (ret == -ERESTARTNOHAND)
-                               ret = -EINTR;
-               }
-       }
+       ret = core_sys_select(n, inp, outp, exp, &end_time);
+       ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
 
        if (ret == -ERESTARTNOHAND) {
                /*
@@ -498,7 +572,7 @@ sticky:
                if (sigmask) {
                        memcpy(&current->saved_sigmask, &sigsaved,
                                        sizeof(sigsaved));
-                       set_thread_flag(TIF_RESTORE_SIGMASK);
+                       set_restore_sigmask();
                }
        } else if (sigmask)
                sigprocmask(SIG_SETMASK, &sigsaved, NULL);
@@ -528,7 +602,7 @@ asmlinkage long sys_pselect6(int n, fd_set __user *inp, fd_set __user *outp,
 
        return sys_pselect7(n, inp, outp, exp, tsp, up, sigsetsize);
 }
-#endif /* TIF_RESTORE_SIGMASK */
+#endif /* HAVE_SET_RESTORE_SIGMASK */
 
 struct poll_list {
        struct poll_list *next;
@@ -573,18 +647,24 @@ static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait)
 }
 
 static int do_poll(unsigned int nfds,  struct poll_list *list,
-                  struct poll_wqueues *wait, s64 *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 (!(*timeout))
+       if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
                pt = NULL;
+               timed_out = 1;
+       }
+
+       if (end_time && !timed_out)
+               slack = estimate_accuracy(end_time);
 
        for (;;) {
                struct poll_list *walk;
-               long __timeout;
 
                set_current_state(TASK_INTERRUPTIBLE);
                for (walk = list; walk != NULL; walk = walk->next) {
@@ -616,27 +696,21 @@ static int do_poll(unsigned int nfds,  struct poll_list *list,
                        if (signal_pending(current))
                                count = -EINTR;
                }
-               if (count || !*timeout)
+               if (count || timed_out)
                        break;
 
-               if (*timeout < 0) {
-                       /* Wait indefinitely */
-                       __timeout = MAX_SCHEDULE_TIMEOUT;
-               } else if (unlikely(*timeout >= (s64)MAX_SCHEDULE_TIMEOUT-1)) {
-                       /*
-                        * Wait for longer than MAX_SCHEDULE_TIMEOUT. Do it in
-                        * a loop
-                        */
-                       __timeout = MAX_SCHEDULE_TIMEOUT - 1;
-                       *timeout -= __timeout;
-               } else {
-                       __timeout = *timeout;
-                       *timeout = 0;
+               /*
+                * 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;
                }
 
-               __timeout = schedule_timeout(__timeout);
-               if (*timeout >= 0)
-                       *timeout += __timeout;
+               if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS))
+                       timed_out = 1;
        }
        __set_current_state(TASK_RUNNING);
        return count;
@@ -645,7 +719,8 @@ static int do_poll(unsigned int nfds,  struct poll_list *list,
 #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, s64 *timeout)
+int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
+               struct timespec *end_time)
 {
        struct poll_wqueues table;
        int err = -EFAULT, fdcount, len, size;
@@ -685,7 +760,7 @@ int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, s64 *timeout)
        }
 
        poll_initwait(&table);
-       fdcount = do_poll(nfds, head, &table, timeout);
+       fdcount = do_poll(nfds, head, &table, end_time);
        poll_freewait(&table);
 
        for (walk = head; walk; walk = walk->next) {
@@ -711,16 +786,21 @@ out_fds:
 
 static long do_restart_poll(struct restart_block *restart_block)
 {
-       struct pollfd __user *ufds = (struct pollfd __user*)restart_block->arg0;
-       int nfds = restart_block->arg1;
-       s64 timeout = ((s64)restart_block->arg3<<32) | (s64)restart_block->arg2;
+       struct pollfd __user *ufds = restart_block->poll.ufds;
+       int nfds = restart_block->poll.nfds;
+       struct timespec *to = NULL, end_time;
        int ret;
 
-       ret = do_sys_poll(ufds, nfds, &timeout);
+       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;
-               restart_block->arg2 = timeout & 0xFFFFFFFF;
-               restart_block->arg3 = (u64)timeout >> 32;
                ret = -ERESTART_RESTARTBLOCK;
        }
        return ret;
@@ -729,57 +809,53 @@ static long do_restart_poll(struct restart_block *restart_block)
 asmlinkage long sys_poll(struct pollfd __user *ufds, unsigned int nfds,
                        long timeout_msecs)
 {
-       s64 timeout_jiffies;
+       struct timespec end_time, *to = NULL;
        int ret;
 
-       if (timeout_msecs > 0) {
-#if HZ > 1000
-               /* We can only overflow if HZ > 1000 */
-               if (timeout_msecs / 1000 > (s64)0x7fffffffffffffffULL / (s64)HZ)
-                       timeout_jiffies = -1;
-               else
-#endif
-                       timeout_jiffies = msecs_to_jiffies(timeout_msecs);
-       } else {
-               /* Infinite (< 0) or no (0) timeout */
-               timeout_jiffies = timeout_msecs;
+       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, &timeout_jiffies);
+       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->arg0 = (unsigned long)ufds;
-               restart_block->arg1 = nfds;
-               restart_block->arg2 = timeout_jiffies & 0xFFFFFFFF;
-               restart_block->arg3 = (u64)timeout_jiffies >> 32;
+               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;
 }
 
-#ifdef TIF_RESTORE_SIGMASK
+#ifdef HAVE_SET_RESTORE_SIGMASK
 asmlinkage long sys_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;
-       s64 timeout = -1;
+       struct timespec ts, end_time, *to = NULL;
        int ret;
 
        if (tsp) {
                if (copy_from_user(&ts, tsp, sizeof(ts)))
                        return -EFAULT;
 
-               /* Cast to u64 to make GCC stop complaining */
-               if ((u64)ts.tv_sec >= (u64)MAX_INT64_SECONDS)
-                       timeout = -1;   /* infinite */
-               else {
-                       timeout = DIV_ROUND_UP(ts.tv_nsec, NSEC_PER_SEC/HZ);
-                       timeout += ts.tv_sec * HZ;
-               }
+               to = &end_time;
+               if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
+                       return -EINVAL;
        }
 
        if (sigmask) {
@@ -793,7 +869,7 @@ asmlinkage long sys_ppoll(struct pollfd __user *ufds, unsigned int nfds,
                sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
        }
 
-       ret = do_sys_poll(ufds, nfds, &timeout);
+       ret = do_sys_poll(ufds, nfds, to);
 
        /* We can restart this syscall, usually */
        if (ret == -EINTR) {
@@ -805,38 +881,14 @@ asmlinkage long sys_ppoll(struct pollfd __user *ufds, unsigned int nfds,
                if (sigmask) {
                        memcpy(&current->saved_sigmask, &sigsaved,
                                        sizeof(sigsaved));
-                       set_thread_flag(TIF_RESTORE_SIGMASK);
+                       set_restore_sigmask();
                }
                ret = -ERESTARTNOHAND;
        } else if (sigmask)
                sigprocmask(SIG_SETMASK, &sigsaved, NULL);
 
-       if (tsp && timeout >= 0) {
-               struct timespec rts;
-
-               if (current->personality & STICKY_TIMEOUTS)
-                       goto sticky;
-               /* Yes, we know it's actually an s64, but it's also positive. */
-               rts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) *
-                                               1000;
-               rts.tv_sec = timeout;
-               if (timespec_compare(&rts, &ts) >= 0)
-                       rts = ts;
-               if (copy_to_user(tsp, &rts, sizeof(rts))) {
-               sticky:
-                       /*
-                        * 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.
-                        */
-                       if (ret == -ERESTARTNOHAND && timeout >= 0)
-                               ret = -EINTR;
-               }
-       }
+       ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
 
        return ret;
 }
-#endif /* TIF_RESTORE_SIGMASK */
+#endif /* HAVE_SET_RESTORE_SIGMASK */