From: Greg KH <gregkh@linuxfoundation.org>
To: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: jakub.kicinski@netronome.com, nbroeking@me.com,
ming.lei@redhat.com, mfuzzey@parkeon.com, ebiederm@xmission.com,
dmitry.torokhov@gmail.com, wagi@monom.org, dwmw2@infradead.org,
jewalt@lgsinnovations.com, rafal@milecki.pl,
arend.vanspriel@broadcom.com, rjw@rjwysocki.net,
yi1.li@linux.intel.com, atull@kernel.org,
moritz.fischer@ettus.com, pmladek@suse.com,
johannes.berg@intel.com, emmanuel.grumbach@intel.com,
luciano.coelho@intel.com, kvalo@codeaurora.org, luto@kernel.org,
torvalds@linux-foundation.org, keescook@chromium.org,
takahiro.akashi@linaro.org, dhowells@redhat.com,
pjones@redhat.com, hdegoede@redhat.com, alan@linux.intel.com,
tytso@mit.edu, paul.gortmaker@windriver.com, mtosatti@redhat.com,
mawilcox@microsoft.com, linux-kernel@vger.kernel.org,
"[4.10+]" <stable@vger.kernel.org>
Subject: Re: [PATCH v2] firmware: fix batched requests - wake all waiters
Date: Thu, 29 Jun 2017 17:17:15 +0200 [thread overview]
Message-ID: <20170629151715.GA5082@kroah.com> (raw)
In-Reply-To: <20170629151641.GC4880@kroah.com>
On Thu, Jun 29, 2017 at 05:16:41PM +0200, Greg KH wrote:
> On Mon, Jun 26, 2017 at 02:23:12PM -0700, Luis R. Rodriguez wrote:
> > From: Jakub Kicinski <jakub.kicinski@netronome.com>
> >
> > The firmware cache mechanism serves two purposes, the secondary purpose is
> > not well documented nor understood. This fixes a regression with the secondary
> > purpose of the firmware cache mechanism: batched requests.
> >
> > The firmware cache is used for:
> >
> > 1) Addressing races with file lookups during the suspend/resume cycle
> > by keeping firmware in memory during the cycle
> >
> > 2) Batched requests for the same file rely only on work from the first file
> > lookup, which keeps the firmware in memory until the last release_firmware()
> > is called
> >
> > Batched requests *only* take effect if secondary requests come in prior to the
> > first user calling release_firmware(). The devres name used for the internal
> > firmware cache is used as a hint other pending requests are ongoing, the
> > firmware buffer data is kept in memory until the last user of the buffer
> > calls release_firmware(), therefore serializing requests and delaying the
> > release until all requests are done.
> >
> > Batched requests wait for a wakup or signal (we only accept SIGKILL now) so we
> > can rely on the first file fetch to write to the pending secondary requests.
> > Commit 5b029624948d ("firmware: do not use fw_lock for fw_state protection")
> > ported the firmware API to use swait, and in doing so failed to convert
> > complete_all() to swake_up_all() -- it used swake_up(), loosing the ability
> > for *some* batched requests to take effect.
> >
> > Without this fix it has been reported plugging in two Intel 6260 Wifi cards
> > on a system will end up enumerating the two devices only 50% of the time
> > [0]. The ported swake_up() should have actually two devices, however,
> > *if more than two cards are used* the swake_up() would not suffice. This
> > change is only part of the required fixes for batched requests. Subsequent
> > fixes will follow.
> >
> > This particular change should fix the cases where more than three requests
> > with the same firmware name is used, otherwise batched requests will wait for
> > MAX_SCHEDULE_TIMEOUT and just timeout eventually.
> >
> > [0] https://bugzilla.kernel.org/show_bug.cgi?id=195477
> >
> > Fixes: 5b029624948d ("firmware: do not use fw_lock for fw_state protection")
> > CC: <stable@vger.kernel.org> [4.10+]
> > Cc: Ming Lei <ming.lei@redhat.com>
> > Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
> > [mcgrof: expanded on impact on commit log]
> > Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> > ---
> >
> > Greg, I think it would make sense to queue this in after the signal stable
> > fixes [1].
>
> As I just dropped them, can you redo this based on Linus's tree now?
Oh nevermind, it does apply to that tree now. Wait, what am I supposed
to do here?
confused,
greg k-h
next prev parent reply other threads:[~2017-06-29 15:17 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-23 23:37 [PATCH] firmware: wake all waiters Jakub Kicinski
2017-06-26 21:20 ` Luis R. Rodriguez
2017-06-26 21:23 ` [PATCH v2] firmware: fix batched requests - " Luis R. Rodriguez
2017-06-29 15:16 ` Greg KH
2017-06-29 15:17 ` Greg KH [this message]
2017-06-29 17:36 ` Luis R. Rodriguez
2017-06-26 23:41 ` [PATCH] firmware: " Luis R. Rodriguez
2017-06-27 2:10 ` Jakub Kicinski
2017-06-27 16:39 ` Luis R. Rodriguez
2017-06-27 21:25 ` Jakub Kicinski
2017-06-27 22:24 ` Luis R. Rodriguez
2017-06-27 22:39 ` Jakub Kicinski
2017-06-27 23:50 ` Luis R. Rodriguez
2017-06-28 7:06 ` [systemd-devel] " Lennart Poettering
2017-06-28 16:06 ` Luis R. Rodriguez
2017-06-28 16:21 ` Lennart Poettering
2017-06-28 17:57 ` Luis R. Rodriguez
2017-06-29 19:56 ` Daniel Wagner
2017-06-27 17:48 ` Bjorn Andersson
2017-06-27 18:03 ` Luis R. Rodriguez
2017-06-27 18:59 ` Bjorn Andersson
2017-06-27 19:08 ` Luis R. Rodriguez
2017-06-27 19:52 ` Bjorn Andersson
2017-06-27 20:24 ` Luis R. Rodriguez
2017-06-26 21:44 ` Linus Torvalds
2017-06-26 23:30 ` Luis R. Rodriguez
2017-06-26 23:43 ` Linus Torvalds
2017-06-27 0:15 ` Luis R. Rodriguez
2017-06-28 13:45 ` Davidlohr Bueso
2017-06-28 15:58 ` Luis R. Rodriguez
2017-06-28 19:03 ` Davidlohr Bueso
2017-06-29 19:08 ` Davidlohr Bueso
2017-06-29 19:48 ` Luis R. Rodriguez
2017-06-30 16:32 ` Davidlohr Bueso
2017-07-05 16:18 ` Peter Zijlstra
2017-07-05 16:33 ` Linus Torvalds
2017-07-12 18:45 ` Luis R. Rodriguez
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