The patch titled
eventfd/kaio integration fix
has been removed from the -mm tree. Its filename was
eventfd-kaio-integration-fix.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: eventfd/kaio integration fix
From: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
Jeff Roberson discovered a race when using kaio eventfd based notifications.
When it occurs it can lead tomissed wakeups and hung userspace.
This patch fixes the race by moving the notification inside the spinlocked
section of kaio. The operation is safe since eventfd spinlock and kaio one
are unrelated.
Signed-off-by: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
Cc: Zach Brown <zach.brown@xxxxxxxxxx>
Cc: Jeff Roberson <jroberson@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/aio.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff -puN fs/aio.c~eventfd-kaio-integration-fix fs/aio.c
--- a/fs/aio.c~eventfd-kaio-integration-fix
+++ a/fs/aio.c
@@ -936,14 +936,6 @@ int aio_complete(struct kiocb *iocb, lon
return 1;
}
- /*
- * Check if the user asked us to deliver the result through an
- * eventfd. The eventfd_signal() function is safe to be called
- * from IRQ context.
- */
- if (!IS_ERR(iocb->ki_eventfd))
- eventfd_signal(iocb->ki_eventfd, 1);
-
info = &ctx->ring_info;
/* add a completion event to the ring buffer.
@@ -992,6 +984,15 @@ int aio_complete(struct kiocb *iocb, lon
kunmap_atomic(ring, KM_IRQ1);
pr_debug("added to ring %p at [%lu]\n", iocb, tail);
+
+ /*
+ * Check if the user asked us to deliver the result through an
+ * eventfd. The eventfd_signal() function is safe to be called
+ * from IRQ context.
+ */
+ if (!IS_ERR(iocb->ki_eventfd))
+ eventfd_signal(iocb->ki_eventfd, 1);
+
put_rq:
/* everything turned out well, dispose of the aiocb. */
ret = __aio_put_req(ctx, iocb);
_
Patches currently in -mm which might be from davidel@xxxxxxxxxxxxxxx are
epoll-avoid-kmemcheck-warning.patch
fs-timerfdc-should-include-linux-syscallsh.patch
signals-send_signal-be-paranoid-about-signalfd_notify.patch
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