From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1524732350; cv=none; d=google.com; s=arc-20160816; b=ONFgfxxnq4wDd2MkOKvbpPfN6HZ5xhfIGWu9bZupMlFy1c3QW7DkOdXJV2iYk0BmuS lszs45AS7bBWsV/qpXsN/fSDXf4/+yyioxpVMGHzd0yfATqQ+ioS3/CcbwUwwTf1U3Mw fFMOrLQOwX90jfCTKMBEcyI98QdIfNDi4V9zuUcEu/2GJOkgjgUvAurrfDO+Id6Ps+A/ 6uLkLf8LX7RXgRO2JpmEl1MX4pwZU0g/nSFNvNC1X1Ja2A/QS6Pnv9nPROk1r3b6M3LO /z6xKiCETfKV1uYdjfOvEGgYU82mXIyyqykX3lbVl2UXMmyeuHHll0rwRTHaggN2QVcQ KiAg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:references:in-reply-to:sender :mime-version:dkim-signature:arc-authentication-results; bh=5PFvN7umsxkCEy2XpAHtlgcNWA/CibLzrLgXqA7lfdY=; b=m/W2RbldqqFIRnD/JUPl8MdkEn13CkHkIVqU2afWNaUxhEHakQGdUGPW52jli9urKE cKzLZPW4x3S5wIXTQI4le9A1pclJRvHfHFIaXQyFgAtOGndkR0mji+ydWzc3ekJMYsdh wXsKxNI6Gx4DHyU82I8qGnB7sHNFy7fwqE3WzZ7FWPvmvFI9KJ06v21fadjNszT2ivo3 40Of3wP3sig8wVTIIZE07O4G9dzgnh/mGO9ixrnv0Yf0m69O6XVAH+FsX7jPhNuDWUM0 lKFOlUkU+I3gfoxRdz6w/2/Hlvc2HMoqxKIrfIK4UDp4XTabuOoKeLh0W6I+Or4ZlL+6 dd+w== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=Ks8GTmJm; spf=pass (google.com: domain of geert.uytterhoeven@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=geert.uytterhoeven@gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=Ks8GTmJm; spf=pass (google.com: domain of geert.uytterhoeven@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=geert.uytterhoeven@gmail.com X-Google-Smtp-Source: AIpwx4+bKn+aKEIxeJjnkEh5Mv+gkQEaRakeydEoAUBJLW+QMP48IIl5nmNYLqcyZT56rmn7ZhB7rAsk3P/tlwFDBp8= MIME-Version: 1.0 Sender: geert.uytterhoeven@gmail.com In-Reply-To: <20180426083542.GA31073@kroah.com> References: <1523366506-19832-1-git-send-email-geert+renesas@glider.be> <1523366506-19832-3-git-send-email-geert+renesas@glider.be> <20180425160645.GA16732@kroah.com> <20180426070410.GM14025@kroah.com> <20180426083542.GA31073@kroah.com> From: Geert Uytterhoeven Date: Thu, 26 Apr 2018 10:45:49 +0200 X-Google-Sender-Auth: T8AcLMTHAcm24CuJaAvJl7L8ZHA Message-ID: Subject: Re: [PATCH v2 2/4] ARM: amba: Fix race condition with driver_override To: Greg Kroah-Hartman Cc: Geert Uytterhoeven , Russell King , Adrian Salido , Nicolai Stange , Sasha Levin , Todd Kjos , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1597365566189003865?= X-GMAIL-MSGID: =?utf-8?q?1598797749023491363?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Hi Greg, On Thu, Apr 26, 2018 at 10:35 AM, Greg Kroah-Hartman wrote: > On Thu, Apr 26, 2018 at 09:40:08AM +0200, Geert Uytterhoeven wrote: >> On Thu, Apr 26, 2018 at 9:04 AM, Greg Kroah-Hartman >> wrote: >> > On Wed, Apr 25, 2018 at 07:53:06PM +0200, Geert Uytterhoeven wrote: >> >> On Wed, Apr 25, 2018 at 6:06 PM, Greg Kroah-Hartman >> >> wrote: >> >> > On Tue, Apr 10, 2018 at 03:21:44PM +0200, Geert Uytterhoeven wrote: >> >> >> The driver_override implementation is susceptible to a race condition >> >> >> when different threads are reading vs storing a different driver >> >> >> override. Add locking to avoid this race condition. >> >> >> >> >> >> Cfr. commits 6265539776a0810b ("driver core: platform: fix race >> >> >> condition with driver_override") and 9561475db680f714 ("PCI: Fix race >> >> >> condition with driver_override"). >> >> >> >> >> >> Fixes: 3cf385713460eb2b ("ARM: 8256/1: driver coamba: add device binding path 'driver_override'") >> >> >> Signed-off-by: Geert Uytterhoeven >> >> >> Reviewed-by: Todd Kjos >> >> >> Cc: stable >> >> >> >> > As this should go to stable kernels, I've fixed it up to apply without >> >> > patch 1 as that's not a real "fix" that anyone needs... >> >> > >> >> > Please try to remember to put fixes first, and then "trivial" things >> >> > later on in a series. >> >> >> >> I did it on purpose, as the fix is much more ugly without patch 1 applied. >> >> Can't you just take patch 1, too? More consistency is always nice, even for >> >> stable ;-) >> > >> > Consistency is nice, but when you have bug fixes that rely on "trivial" >> > patches, it's usually not nice :( >> > >> > I already committed patch 2 to my tree without 1, so let's leave it >> > as-is for now. >> >> Unfortunately the version you committed is buggy: the race condition >> also covers the NULL check removed by the trivial patch you skipped, >> so now you can get inconsistent behavior (no output or "(null)") on the >> same running kernel version... >> >> Please revert and apply both. Thanks! > > Ugh, you are right, sorry about that. > > I've reverted the offending patch, and added them in the correct order > now, I should have listened to you :) Np, issue detected and fixed. Thanks! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds