Commit-ID: 536ebe9ca999f6d0903d91698678ccc1742e8dd9
Gitweb: http://git.kernel.org/tip/536ebe9ca999f6d0903d91698678ccc1742e8dd9
Author: Peter Zijlstra <[email protected]>
AuthorDate: Tue, 16 Dec 2014 16:28:38 +0100
Committer: Ingo Molnar <[email protected]>
CommitDate: Fri, 9 Jan 2015 11:18:12 +0100
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 <[email protected]>
Reported-by: Sedat Dilek <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Eric Paris <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Eric Paris <[email protected]>
Link:
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
fs/notify/fanotify/fanotify_user.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/fs/notify/fanotify/fanotify_user.c
b/fs/notify/fanotify/fanotify_user.c
index c991616..bff8567 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -259,16 +259,15 @@ static ssize_t fanotify_read(struct file *file, char
__user *buf,
struct fsnotify_event *kevent;
char __user *start;
int ret;
- DEFINE_WAIT(wait);
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
start = buf;
group = file->private_data;
pr_debug("%s: group=%p\n", __func__, group);
+ add_wait_queue(&group->notification_waitq, &wait);
while (1) {
- prepare_to_wait(&group->notification_waitq, &wait,
TASK_INTERRUPTIBLE);
-
mutex_lock(&group->notification_mutex);
kevent = get_one_event(group, count);
mutex_unlock(&group->notification_mutex);
@@ -289,7 +288,8 @@ static ssize_t fanotify_read(struct file *file, char __user
*buf,
if (start != buf)
break;
- schedule();
+
+ wait_woken(&wait, TASK_INTERRUPTIBLE,
MAX_SCHEDULE_TIMEOUT);
continue;
}
@@ -318,8 +318,8 @@ static ssize_t fanotify_read(struct file *file, char __user
*buf,
buf += ret;
count -= ret;
}
+ remove_wait_queue(&group->notification_waitq, &wait);
- finish_wait(&group->notification_waitq, &wait);
if (start != buf && ret != -EFAULT)
ret = buf - start;
return ret;
--
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