From: Sandeep Patil <sspatil@android.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
David Howells <dhowells@redhat.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable <stable@vger.kernel.org>,
Android Kernel Team <kernel-team@android.com>
Subject: Re: [PATCH 1/1] fs: pipe: wakeup readers everytime new data written is to pipe
Date: Fri, 30 Jul 2021 19:47:22 +0000 [thread overview]
Message-ID: <b1688f32-cb0e-04e1-3c91-aa8cddbcf41d@android.com> (raw)
In-Reply-To: <CAHk-=wjStQurUzSAPVajL6Rj=CaPuSSgwaMO=0FJzFvSD66ACw@mail.gmail.com>
On 7/30/21 7:23 PM, Linus Torvalds wrote:
> On Fri, Jul 30, 2021 at 12:11 PM Sandeep Patil <sspatil@android.com> wrote:
>>
>> Yes, your patch fixes all apps on Android I can test that include this
>> library.
>
> Ok, thanks for checking.
>
>> fwiw, the library seems to have been fixed. However, I am not sure
>> how long it will be for all apps to take that update :(.
>
> I wonder if I could make the wakeup logic do this only for the epollet case.
aren't we supposed to wakeup on each write in level-triggered (default)
case though?
>
> I'll have to think about it, but maybe I'll just apply that simple
> patch. I dislike the pointless wakeups, and as long as the only case I
> knew of was only a test of broken behavior, it was fine. But now that
> you've reported actual application breakage, this is in the "real
> regression" category, and so I'll fix it one way or the other.
>
> And on the other hand I also have a slight preference towards your
> patch simply because you did the work of finding this out, so you
> should get the credit.
Ha, I can't really claim credit here. This was also reported to us
in Android that triggered the search. Plus, now that I see your thread
with Michael Kerrisk, he was way ahead of us in finding this out.
>
> I'll mull it over a bit more, but whatever I'll do I'll do before rc4
> and mark it for stable.
Thanks, I was actually going to suggest taking your patch cause it also
makes changes in pipe_read(). I am not sure if there are apps that do
EPOLLET | EPOLLOUT (can't think of a reason why).
- ssp
>
> Thanks for testing,
>
> Linus
>
next prev parent reply other threads:[~2021-07-30 19:48 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-29 22:26 [PATCH 0/1] Revert change in pipe reader wakeup behavior Sandeep Patil
2021-07-29 22:26 ` [PATCH 1/1] fs: pipe: wakeup readers everytime new data written is to pipe Sandeep Patil
2021-07-29 23:01 ` Linus Torvalds
2021-07-30 19:11 ` Sandeep Patil
2021-07-30 19:23 ` Linus Torvalds
2021-07-30 19:47 ` Sandeep Patil [this message]
2021-07-30 22:06 ` Linus Torvalds
2021-07-30 22:53 ` Linus Torvalds
2021-07-30 22:55 ` Linus Torvalds
2021-07-31 5:32 ` Greg Kroah-Hartman
2021-08-02 18:59 ` Sandeep Patil
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