linux-kernel - Re: [PATCH 2/4] swait: add the missing killable swaits

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Message-ID: <20170629155323.06445ddf@cakuba.netronome.com>
Date:   Thu, 29 Jun 2017 15:53:23 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc:     nbroeking@...com, Linus Torvalds <torvalds@...ux-foundation.org>,
        Davidlohr Bueso <dave@...olabs.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg KH <gregkh@...uxfoundation.org>, mfuzzey@...keon.com,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Daniel Wagner <wagi@...om.org>,
        David Woodhouse <dwmw2@...radead.org>,
        jewalt@...innovations.com, rafal@...ecki.pl,
        Arend Van Spriel <arend.vanspriel@...adcom.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "Li, Yi" <yi1.li@...ux.intel.com>, atull@...nel.org,
        Moritz Fischer <moritz.fischer@...us.com>,
        Petr Mladek <pmladek@...e.com>,
        Johannes Berg <johannes.berg@...el.com>,
        Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
        "Coelho, Luciano" <luciano.coelho@...el.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        Andrew Lutomirski <luto@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        "AKASHI, Takahiro" <takahiro.akashi@...aro.org>,
        David Howells <dhowells@...hat.com>,
        Peter Jones <pjones@...hat.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Alan Cox <alan@...ux.intel.com>, Theodore Ts'o <tytso@....edu>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Linux API <linux-api@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "stable # 4 . 6" <stable@...r.kernel.org>
Subject: Re: [PATCH 2/4] swait: add the missing killable swaits

On Fri, 30 Jun 2017 00:50:03 +0200, Luis R. Rodriguez wrote:
> On Thu, Jun 29, 2017 at 01:58:22PM -0700, Jakub Kicinski wrote:
> > On Thu, 29 Jun 2017 21:44:55 +0200, Luis R. Rodriguez wrote:  
> > > > Since this swake_up() --> swake_up_all() reportedly *fixed* the one wake up
> > > > issue it would seem this does queue [0]. That said, I don't see any simple tests
> > > > tools/testing/selftests/swait but then again we don't have test for regular
> > > > waits either...
> > > > 
> > > > [0] https://bugzilla.kernel.org/show_bug.cgi?id=195477    
> > > 
> > > I should also note that the swake_up_all() should have only helped in cases where
> > > 3 cards were used, as if only 2 were used that should have been covered by just
> > > the swake_up(). Unless of course I hear otherwise by the reporter, Nicolas or
> > > from Jakub.  
> > 
> > I was hitting this with 2 cards.  
> 
> Thanks!
> 
> Thing is I'm not convinced the issue with 2 cards was the swake_up() Vs
> swake_up_all() in this case though. Let's recall also the missing wake up on
> errors! And the fact that netronome has optional firmware, which naturally can
> fail.
> 
> So could the issue with 2 cards instead of the miss of a wake up on error due
> to batched requests ? If so then that still would not put blame on the
> swake_up()!

Sorry, that was during manual tests.  I had the driver request the
firmware with _nowait() without an uevent, and then after I manually
wrote -1 to loading only one would get woken up.