tcp: enforce tcp_min_snd_mss in tcp_mtu_probing()

[pandora-kernel.git] / mm / backing-dev.c

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 71034f4..845e58b 100644 (file)
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -318,7 +318,7 @@ static void wakeup_timer_fn(unsigned long data)
        if (bdi->wb.task) {
                trace_writeback_wake_thread(bdi);
                wake_up_process(bdi->wb.task);
-       } else {
+       } else if (bdi->dev) {
                /*
                 * When bdi tasks are inactive for long time, they are killed.
                 * In this case we have to wake-up the forker thread which
@@ -584,6 +584,8 @@ EXPORT_SYMBOL(bdi_register_dev);
  */
 static void bdi_wb_shutdown(struct backing_dev_info *bdi)
 {
+       struct task_struct *task;
+
        if (!bdi_cap_writeback_dirty(bdi))
                return;
 
@@ -604,9 +606,14 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
         * unfreeze of the thread before calling kthread_stop(), otherwise
         * it would never exet if it is currently stuck in the refrigerator.
         */
-       if (bdi->wb.task) {
-               thaw_process(bdi->wb.task);
-               kthread_stop(bdi->wb.task);
+       spin_lock_bh(&bdi->wb_lock);
+       task = bdi->wb.task;
+       bdi->wb.task = NULL;
+       spin_unlock_bh(&bdi->wb_lock);
+
+       if (task) {
+               thaw_process(task);
+               kthread_stop(task);
        }
 }
 
@@ -627,7 +634,9 @@ static void bdi_prune_sb(struct backing_dev_info *bdi)
 
 void bdi_unregister(struct backing_dev_info *bdi)
 {
-       if (bdi->dev) {
+       struct device *dev = bdi->dev;
+
+       if (dev) {
                bdi_set_min_ratio(bdi, 0);
                trace_writeback_bdi_unregister(bdi);
                bdi_prune_sb(bdi);
@@ -636,8 +645,12 @@ void bdi_unregister(struct backing_dev_info *bdi)
                if (!bdi_cap_flush_forker(bdi))
                        bdi_wb_shutdown(bdi);
                bdi_debug_unregister(bdi);
-               device_unregister(bdi->dev);
+
+               spin_lock_bh(&bdi->wb_lock);
                bdi->dev = NULL;
+               spin_unlock_bh(&bdi->wb_lock);
+
+               device_unregister(dev);
        }
 }
 EXPORT_SYMBOL(bdi_unregister);
@@ -834,8 +847,9 @@ EXPORT_SYMBOL(congestion_wait);
  * jiffies for either a BDI to exit congestion of the given @sync queue
  * or a write to complete.
  *
- * In the absence of zone congestion, cond_resched() is called to yield
- * the processor if necessary but otherwise does not sleep.
+ * In the absence of zone congestion, a short sleep or a cond_resched is
+ * performed to yield the processor and to allow other subsystems to make
+ * a forward progress.
  *
  * The return value is 0 if the sleep is for the full timeout. Otherwise,
  * it is the number of jiffies that were still remaining when the function
@@ -855,7 +869,19 @@ long wait_iff_congested(struct zone *zone, int sync, long timeout)
         */
        if (atomic_read(&nr_bdi_congested[sync]) == 0 ||
                        !zone_is_reclaim_congested(zone)) {
-               cond_resched();
+
+               /*
+                * Memory allocation/reclaim might be called from a WQ
+                * context and the current implementation of the WQ
+                * concurrency control doesn't recognize that a particular
+                * WQ is congested if the worker thread is looping without
+                * ever sleeping. Therefore we have to do a short sleep
+                * here rather than calling cond_resched().
+                */
+               if (current->flags & PF_WQ_WORKER)
+                       schedule_timeout_uninterruptible(1);
+               else
+                       cond_resched();
 
                /* In case we scheduled, work out time remaining */
                ret = timeout - (jiffies - start);