lkml.org 
[lkml]   [2011]   [Mar]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] [221/275] aio: wake all waiters when destroying ctx
Date
2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Roland Dreier <roland@purestorage.com>
commit e91f90bb0bb10be9cc8efd09a3cf4ecffcad0db1 upstream.

The test program below will hang because io_getevents() uses
add_wait_queue_exclusive(), which means the wake_up() in io_destroy() only
wakes up one of the threads. Fix this by using wake_up_all() in the aio
code paths where we want to make sure no one gets stuck.

// t.c -- compile with gcc -lpthread -laio t.c
#include <libaio.h>
#include <pthread.h>
#include <stdio.h>
#include <unistd.h>

static const int nthr = 2;

void *getev(void *ctx)
{
struct io_event ev;
io_getevents(ctx, 1, 1, &ev, NULL);
printf("io_getevents returned\n");
return NULL;
}
int main(int argc, char *argv[])
{
io_context_t ctx = 0;
pthread_t thread[nthr];
int i;
io_setup(1024, &ctx);

for (i = 0; i < nthr; ++i)
pthread_create(&thread[i], NULL, getev, ctx);

sleep(1);

io_destroy(ctx);

for (i = 0; i < nthr; ++i)
pthread_join(thread[i], NULL);

return 0;
}
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/aio.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
Index: linux-2.6.35.y/fs/aio.c
===================================================================
--- linux-2.6.35.y.orig/fs/aio.c 2011-03-29 22:50:28.449530467 -0700
+++ linux-2.6.35.y/fs/aio.c 2011-03-29 23:03:02.843227419 -0700
@@ -512,7 +512,7 @@
ctx->reqs_active--;

if (unlikely(!ctx->reqs_active && ctx->dead))
- wake_up(&ctx->wait);
+ wake_up_all(&ctx->wait);
}

static void aio_fput_routine(struct work_struct *data)
@@ -1233,7 +1233,7 @@
* by other CPUs at this point. Right now, we rely on the
* locking done by the above calls to ensure this consistency.
*/
- wake_up(&ioctx->wait);
+ wake_up_all(&ioctx->wait);
put_ioctx(ioctx); /* once for the lookup */
}


\
 
 \ /
  Last update: 2011-03-30 23:25    [from the cache]
©2003-2011 Jasper Spaans