2011-04-14 20:39:51

by Darren Hart

Subject: [PATCH V3] futex: set FLAGS_HAS_TIMEOUT during demux for FUTEX_WAIT

The FLAGS_HAS_TIMEOUT flag was not getting set, causing the restart_block to
restart futex_wait() without a timeout after a signal.

Commit b41277dc7a18ee332d in 2.6.38 introduced the regression by accidentally
removing the the FLAGS_HAS_TIMEOUT assignment from futex_wait() during the setup
of the restart block. Restore the originaly behavior.

Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=32922

V2: Added references to commit message.
V3: Set flag during restart block instead of do_futex()

Signed-off-by: Darren Hart <[email protected]>
Reported-by: Tim Smith <[email protected]>
Reported-by: Torsten Hilbrich <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ingo Molnar <[email protected]>
CC: Eric Dumazet <[email protected]>
CC: John Kacur <[email protected]>
---
kernel/futex.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index bda4157..9d9c476 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1887,6 +1887,7 @@ retry:
restart->futex.time = abs_time->tv64;
restart->futex.bitset = bitset;
restart->futex.flags = flags;
+ flags |= FLAGS_HAS_TIMEOUT;

ret = -ERESTART_RESTARTBLOCK;

--
1.7.1

2011-04-14 20:43:22

by Eric Dumazet

Subject: Re: [PATCH V3] futex: set FLAGS_HAS_TIMEOUT during demux for FUTEX_WAIT

Le jeudi 14 avril 2011 à 13:39 -0700, Darren Hart a écrit :
> The FLAGS_HAS_TIMEOUT flag was not getting set, causing the restart_block to
> restart futex_wait() without a timeout after a signal.
>
> Commit b41277dc7a18ee332d in 2.6.38 introduced the regression by accidentally
> removing the the FLAGS_HAS_TIMEOUT assignment from futex_wait() during the setup
> of the restart block. Restore the originaly behavior.
>
> Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=32922
>
> V2: Added references to commit message.
> V3: Set flag during restart block instead of do_futex()
>
> Signed-off-by: Darren Hart <[email protected]>
> Reported-by: Tim Smith <[email protected]>
> Reported-by: Torsten Hilbrich <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> CC: Eric Dumazet <[email protected]>
> CC: John Kacur <[email protected]>
> ---
> kernel/futex.c | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/futex.c b/kernel/futex.c
> index bda4157..9d9c476 100644
> --- a/kernel/futex.c
> +++ b/kernel/futex.c
> @@ -1887,6 +1887,7 @@ retry:
> restart->futex.time = abs_time->tv64;
> restart->futex.bitset = bitset;
> restart->futex.flags = flags;
> + flags |= FLAGS_HAS_TIMEOUT;
>
> ret = -ERESTART_RESTARTBLOCK;
>


Hmmm, I am sorry but this wont work... please try :

- restart->futex.flags = flags;
+ restart->futex.flags = flags | FLAGS_HAS_TIMEOUT;

2011-04-14 20:48:11

by Darren Hart

Subject: Re: [PATCH V3] futex: set FLAGS_HAS_TIMEOUT during demux for FUTEX_WAIT

On 04/14/2011 01:43 PM, Eric Dumazet wrote:
> Le jeudi 14 avril 2011 à 13:39 -0700, Darren Hart a écrit :
>> The FLAGS_HAS_TIMEOUT flag was not getting set, causing the restart_block to
>> restart futex_wait() without a timeout after a signal.
>>
>> Commit b41277dc7a18ee332d in 2.6.38 introduced the regression by accidentally
>> removing the the FLAGS_HAS_TIMEOUT assignment from futex_wait() during the setup
>> of the restart block. Restore the originaly behavior.
>>
>> Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=32922
>>
>> V2: Added references to commit message.
>> V3: Set flag during restart block instead of do_futex()
>>
>> Signed-off-by: Darren Hart <[email protected]>
>> Reported-by: Tim Smith <[email protected]>
>> Reported-by: Torsten Hilbrich <[email protected]>
>> Cc: Thomas Gleixner <[email protected]>
>> Cc: Peter Zijlstra <[email protected]>
>> Cc: Ingo Molnar <[email protected]>
>> CC: Eric Dumazet <[email protected]>
>> CC: John Kacur <[email protected]>
>> ---
>> kernel/futex.c | 1 +
>> 1 files changed, 1 insertions(+), 0 deletions(-)
>>
>> diff --git a/kernel/futex.c b/kernel/futex.c
>> index bda4157..9d9c476 100644
>> --- a/kernel/futex.c
>> +++ b/kernel/futex.c
>> @@ -1887,6 +1887,7 @@ retry:
>> restart->futex.time = abs_time->tv64;
>> restart->futex.bitset = bitset;
>> restart->futex.flags = flags;
>> + flags |= FLAGS_HAS_TIMEOUT;
>>
>> ret = -ERESTART_RESTARTBLOCK;
>>
>
>
> Hmmm, I am sorry but this wont work... please try :
>
> - restart->futex.flags = flags;
> + restart->futex.flags = flags | FLAGS_HAS_TIMEOUT;

Ah crud... now that's just embarrassing... resending.


--
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel