ACPICA: Fix code divergence of global lock handling
Lin Ming [Wed, 23 Mar 2011 09:26:36 +0000 (17:26 +0800)]
Commit 9cd0314(ACPI / ACPICA: Fix global lock acquisition) was backported
into ACPICA code base, and some divergence was introduced.

This patch fixed it,
- rename acpi_ev_global_lock_pending/acpi_ev_global_lock_pending_lock
  to acpi_gbl_global_lock_pending/acpi_gbl_global_lock_pending_lock.

- move the initialization of acpi_gbl_global_lock_pending_lock from
  acpi_ut_mutex_initialize to acpi_ev_init_global_lock_handler.

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Reviewed-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/acpica/acglobal.h
drivers/acpi/acpica/evmisc.c
drivers/acpi/acpica/utmutex.c

index 6d512fc..73863d8 100644 (file)
@@ -214,13 +214,16 @@ ACPI_EXTERN struct acpi_mutex_info acpi_gbl_mutex_info[ACPI_NUM_MUTEX];
 
 /*
  * Global lock mutex is an actual AML mutex object
- * Global lock semaphore works in conjunction with the HW global lock
+ * Global lock semaphore works in conjunction with the actual global lock
+ * Global lock spinlock is used for "pending" handshake
  */
 ACPI_EXTERN union acpi_operand_object *acpi_gbl_global_lock_mutex;
 ACPI_EXTERN acpi_semaphore acpi_gbl_global_lock_semaphore;
+ACPI_EXTERN acpi_spinlock acpi_gbl_global_lock_pending_lock;
 ACPI_EXTERN u16 acpi_gbl_global_lock_handle;
 ACPI_EXTERN u8 acpi_gbl_global_lock_acquired;
 ACPI_EXTERN u8 acpi_gbl_global_lock_present;
+ACPI_EXTERN u8 acpi_gbl_global_lock_pending;
 
 /*
  * Spinlocks are used for interfaces that can be possibly called at
@@ -228,7 +231,6 @@ ACPI_EXTERN u8 acpi_gbl_global_lock_present;
  */
 ACPI_EXTERN acpi_spinlock acpi_gbl_gpe_lock;   /* For GPE data structs and registers */
 ACPI_EXTERN acpi_spinlock acpi_gbl_hardware_lock;      /* For ACPI H/W except GPE registers */
-ACPI_EXTERN acpi_spinlock acpi_ev_global_lock_pending_lock; /* For global lock */
 
 /*****************************************************************************
  *
index 7dc8094..69a3b4a 100644 (file)
@@ -284,39 +284,41 @@ static void ACPI_SYSTEM_XFACE acpi_ev_notify_dispatch(void *context)
  * RETURN:      ACPI_INTERRUPT_HANDLED
  *
  * DESCRIPTION: Invoked directly from the SCI handler when a global lock
- *              release interrupt occurs.  If there's a thread waiting for
- *              the global lock, signal it.
- *
- * NOTE: Assumes that the semaphore can be signaled from interrupt level. If
- * this is not possible for some reason, a separate thread will have to be
- * scheduled to do this.
+ *              release interrupt occurs. If there is actually a pending
+ *              request for the lock, signal the waiting thread.
  *
  ******************************************************************************/
-static u8 acpi_ev_global_lock_pending;
 
 static u32 acpi_ev_global_lock_handler(void *context)
 {
        acpi_status status;
        acpi_cpu_flags flags;
 
-       flags = acpi_os_acquire_lock(acpi_ev_global_lock_pending_lock);
+       flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
 
-       if (!acpi_ev_global_lock_pending) {
-               goto out;
+       /*
+        * If a request for the global lock is not actually pending,
+        * we are done. This handles "spurious" global lock interrupts
+        * which are possible (and have been seen) with bad BIOSs.
+        */
+       if (!acpi_gbl_global_lock_pending) {
+               goto cleanup_and_exit;
        }
 
-       /* Send a unit to the semaphore */
-
+       /*
+        * Send a unit to the global lock semaphore. The actual acquisition
+        * of the global lock will be performed by the waiting thread.
+        */
        status = acpi_os_signal_semaphore(acpi_gbl_global_lock_semaphore, 1);
        if (ACPI_FAILURE(status)) {
                ACPI_ERROR((AE_INFO, "Could not signal Global Lock semaphore"));
        }
 
-       acpi_ev_global_lock_pending = FALSE;
+       acpi_gbl_global_lock_pending = FALSE;
 
- out:
-       acpi_os_release_lock(acpi_ev_global_lock_pending_lock, flags);
+cleanup_and_exit:
 
+       acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
        return (ACPI_INTERRUPT_HANDLED);
 }
 
@@ -350,14 +352,20 @@ acpi_status acpi_ev_init_global_lock_handler(void)
         * Map to AE_OK, but mark global lock as not present. Any attempt to
         * actually use the global lock will be flagged with an error.
         */
+       acpi_gbl_global_lock_present = FALSE;
        if (status == AE_NO_HARDWARE_RESPONSE) {
                ACPI_ERROR((AE_INFO,
                            "No response from Global Lock hardware, disabling lock"));
 
-               acpi_gbl_global_lock_present = FALSE;
                return_ACPI_STATUS(AE_OK);
        }
 
+       status = acpi_os_create_lock(&acpi_gbl_global_lock_pending_lock);
+       if (ACPI_FAILURE(status)) {
+               return_ACPI_STATUS(status);
+       }
+
+       acpi_gbl_global_lock_pending = FALSE;
        acpi_gbl_global_lock_present = TRUE;
        return_ACPI_STATUS(status);
 }
@@ -414,7 +422,7 @@ static int acpi_ev_global_lock_acquired;
 acpi_status acpi_ev_acquire_global_lock(u16 timeout)
 {
        acpi_cpu_flags flags;
-       acpi_status status = AE_OK;
+       acpi_status status;
        u8 acquired = FALSE;
 
        ACPI_FUNCTION_TRACE(ev_acquire_global_lock);
@@ -458,15 +466,15 @@ acpi_status acpi_ev_acquire_global_lock(u16 timeout)
        }
 
        /*
-        * Make sure that a global lock actually exists. If not, just treat the
-        * lock as a standard mutex.
+        * Make sure that a global lock actually exists. If not, just
+        * treat the lock as a standard mutex.
         */
        if (!acpi_gbl_global_lock_present) {
                acpi_gbl_global_lock_acquired = TRUE;
                return_ACPI_STATUS(AE_OK);
        }
 
-       flags = acpi_os_acquire_lock(acpi_ev_global_lock_pending_lock);
+       flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
 
        do {
 
@@ -475,20 +483,19 @@ acpi_status acpi_ev_acquire_global_lock(u16 timeout)
                ACPI_ACQUIRE_GLOBAL_LOCK(acpi_gbl_FACS, acquired);
                if (acquired) {
                        acpi_gbl_global_lock_acquired = TRUE;
-
                        ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
                                          "Acquired hardware Global Lock\n"));
                        break;
                }
 
-               acpi_ev_global_lock_pending = TRUE;
-
-               acpi_os_release_lock(acpi_ev_global_lock_pending_lock, flags);
-
                /*
-                * Did not get the lock. The pending bit was set above, and we
-                * must wait until we get the global lock released interrupt.
+                * Did not get the lock. The pending bit was set above, and
+                * we must now wait until we receive the global lock
+                * released interrupt.
                 */
+               acpi_gbl_global_lock_pending = TRUE;
+               acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
+
                ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
                                  "Waiting for hardware Global Lock\n"));
 
@@ -496,17 +503,16 @@ acpi_status acpi_ev_acquire_global_lock(u16 timeout)
                 * Wait for handshake with the global lock interrupt handler.
                 * This interface releases the interpreter if we must wait.
                 */
-               status = acpi_ex_system_wait_semaphore(
-                                               acpi_gbl_global_lock_semaphore,
-                                               ACPI_WAIT_FOREVER);
+               status =
+                   acpi_ex_system_wait_semaphore
+                   (acpi_gbl_global_lock_semaphore, ACPI_WAIT_FOREVER);
 
-               flags = acpi_os_acquire_lock(acpi_ev_global_lock_pending_lock);
+               flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
 
        } while (ACPI_SUCCESS(status));
 
-       acpi_ev_global_lock_pending = FALSE;
-
-       acpi_os_release_lock(acpi_ev_global_lock_pending_lock, flags);
+       acpi_gbl_global_lock_pending = FALSE;
+       acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
 
        return_ACPI_STATUS(status);
 }
index 519d4ee..7d797e2 100644 (file)
@@ -93,11 +93,6 @@ acpi_status acpi_ut_mutex_initialize(void)
                return_ACPI_STATUS (status);
        }
 
-       status = acpi_os_create_lock (&acpi_ev_global_lock_pending_lock);
-       if (ACPI_FAILURE (status)) {
-               return_ACPI_STATUS (status);
-       }
-
        /* Mutex for _OSI support */
        status = acpi_os_create_mutex(&acpi_gbl_osi_mutex);
        if (ACPI_FAILURE(status)) {