Eric Lee / smarc-ti-linux-kernel

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Commit 536ebe9ca999f6d0903d91698678ccc1742e8dd9

Authored by Peter Zijlstra
Committed by Ingo Molnar
1 parent b74e6278fd
Exists in ti-lsk-linux-4.1.y and in 10 other branches dlt-processor-sdk-linux-03.00.00.04, processor-sdk-linux-02.00.01, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04

sched, fanotify: Deal with nested sleeps 

As per e23738a7300a ("sched, inotify: Deal with nested sleeps").

fanotify_read is a wait loop with sleeps in. Wait loops rely on
task_struct::state and sleeps do too, since that's the only means of
actually sleeping. Therefore the nested sleeps destroy the wait loop
state and the wait loop breaks the sleep functions that assume
TASK_RUNNING (mutex_lock).

Fix this by using the new woken_wake_function and wait_woken() stuff,
which registers wakeups in wait and thereby allows shrinking the
task_state::state changes to the actual sleep part.

Reported-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Eric Paris <eparis@redhat.com>
Link: http://lkml.kernel.org/r/20141216152838.GZ3337@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Showing 1 changed file with 5 additions and 5 deletions Side-by-side Diff

fs/notify/fanotify/fanotify_user.c
Diff comments   View file @ 536ebe9
... ... @@ -259,16 +259,15 @@
259 259 struct fsnotify_event *kevent;
260 260 char __user *start;
261 261 int ret;
262   - DEFINE_WAIT(wait);
  262 + DEFINE_WAIT_FUNC(wait, woken_wake_function);
263 263  
264 264 start = buf;
265 265 group = file->private_data;
266 266  
267 267 pr_debug("%s: group=%p\n", __func__, group);
268 268  
  269 + add_wait_queue(&group->notification_waitq, &wait);
269 270 while (1) {
270   - prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
271   -
272 271 mutex_lock(&group->notification_mutex);
273 272 kevent = get_one_event(group, count);
274 273 mutex_unlock(&group->notification_mutex);
... ... @@ -289,7 +288,8 @@
289 288  
290 289 if (start != buf)
291 290 break;
292   - schedule();
  291 +
  292 + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
293 293 continue;
294 294 }
295 295  
296 296  
... ... @@ -318,8 +318,8 @@
318 318 buf += ret;
319 319 count -= ret;
320 320 }
  321 + remove_wait_queue(&group->notification_waitq, &wait);
321 322  
322   - finish_wait(&group->notification_waitq, &wait);
323 323 if (start != buf && ret != -EFAULT)
324 324 ret = buf - start;
325 325 return ret;