linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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
> 


  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=b1688f32-cb0e-04e1-3c91-aa8cddbcf41d@android.com \
    --to=sspatil@android.com \
    --cc=dhowells@redhat.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=kernel-team@android.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=stable@vger.kernel.org \
    --cc=torvalds@linux-foundation.org \
    --subject='Re: [PATCH 1/1] fs: pipe: wakeup readers everytime new data written is to pipe' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).