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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: Mon, 2 Aug 2021 18:59:03 +0000	[thread overview]
Message-ID: <fc0e2c8a-96cc-7787-6866-3802a1d5c50e@android.com> (raw)
In-Reply-To: <CAHk-=wjrfasYJUaZ-rJmYt9xa=DqmJ5-sVRG7cJ2X8nNcSXp9g@mail.gmail.com>

On 7/30/21 10:53 PM, Linus Torvalds wrote:
> On Fri, Jul 30, 2021 at 12:23 PM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>>
>> I'll mull it over a bit more, but whatever I'll do I'll do before rc4
>> and mark it for stable.
> 
> Ok, I ended up committing the minimal possible change (and fixing up
> the comment above it).
> 
> It's very much *not* the original behavior either, but that original
> behavior was truly insane ("wake up for each hunk written"), and I'm
> trying to at least keep the kernel code from doing actively stupid
> things.
> 
> Since that old patch of mine worked for your test-case, then clearly
> that realm-core library didn't rely on _that_ kind of insane internal
> kernel implementation details exposed as semantics. So The minimal
> patch basically says "each write() system call wil do at least one
> wake-up, whether really necessary or not".
> 
> I also intentionally kept the read side untouched, in that there
> apparently still isn't a case that would need the confused semantics
> for read events.
> 
> End result: the commit message is a lot bigger than the patch, with
> most of it being trying to explain the background.
> 
> I've pushed it out as commit 3a34b13a88ca ("pipe: make pipe writes
> always wake up readers"). Holler if you notice anything odd remaining.

Since what you merged isn't different than what I tested, I don't
expect any surprises but I will test it regardless. I will come back
if I see anything unexpected.

Thanks for the explanation about the default behavior earlier
in the thread.

- ssp

      parent reply	other threads:[~2021-08-02 18:59 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
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 [this message]

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