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From: Davidlohr Bueso <dave@stgolabs.net>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Greg KH <gregkh@linuxfoundation.org>,
	"Luis R. Rodriguez" <mcgrof@kernel.org>,
	mfuzzey@parkeon.com, "Eric W. Biederman" <ebiederm@xmission.com>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Daniel Wagner <wagi@monom.org>,
	David Woodhouse <dwmw2@infradead.org>,
	jewalt@lgsinnovations.com, rafal@milecki.pl,
	Arend Van Spriel <arend.vanspriel@broadcom.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	"Li, Yi" <yi1.li@linux.intel.com>,
	atull@kernel.org, Moritz Fischer <moritz.fischer@ettus.com>,
	Petr Mladek <pmladek@suse.com>,
	Johannes Berg <johannes.berg@intel.com>,
	Emmanuel Grumbach <emmanuel.grumbach@intel.com>,
	"Coelho, Luciano" <luciano.coelho@intel.com>,
	Kalle Valo <kvalo@codeaurora.org>, Andrew Lutomirski <luto@ker>
Subject: Re: [PATCH 2/4] swait: add the missing killable swaits
Date: Thu, 29 Jun 2017 10:40:46 -0700	[thread overview]
Message-ID: <20170629174046.GC3954@linux-80c1.suse> (raw)
In-Reply-To: <CA+55aFxkp51RipBj7__T0hoy6tAdXJxTqjMdhnnnkKm71P6HuQ@mail.gmail.com>

On Thu, 29 Jun 2017, Linus Torvalds wrote:

>Well, I'd actually say it the other way around: swait should not be
>used in general, only in _very_ particular pieces of code that
>actually explicitly need the odd swait semantics.
>
>swait uses special locking and has odd semantics that are not at all
>the same as the default wait queue ones. It should not be used without
>very strong reasons (and honestly, the only strong enough reason seems
>to be "RT").
>
>The special locking means that swait doesn't do DEBUG_LOCK_ALLOC, but
>it also means that it doesn't even work in all contexts.
>
>So "swake_up()" does surprising things (only wake up one - that's what
>caused a firmware loading bug), and "swake_up_all()" has magic rules
>about interrupt disabling.
>
>The thing is simply a collection of small hacks and should NOT be used
>in general.

For all the above, what do you think of my 'sswait' proposal?

Thanks,
Davidlohr

  parent reply	other threads:[~2017-06-29 17:40 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-14 22:20 [PATCH 0/4] firmware: fix fallback mechanism by ignoring SIGCHLD Luis R. Rodriguez
2017-06-14 22:20 ` [PATCH 1/4] test_firmware: add test case for SIGCHLD on sync fallback Luis R. Rodriguez
2017-06-14 22:20 ` [PATCH 2/4] swait: add the missing killable swaits Luis R. Rodriguez
     [not found]   ` <20170614222017.14653-3-mcgrof-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2017-06-29 12:54     ` Greg KH
     [not found]       ` <20170629125402.GH26046-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-06-29 13:05         ` Thomas Gleixner
2017-06-29 13:35           ` Greg KH
2017-06-29 13:46             ` Thomas Gleixner
2017-06-29 16:13               ` Linus Torvalds
2017-06-29 16:31                 ` Matthew Wilcox
2017-06-29 17:29                   ` Luis R. Rodriguez
2017-06-29 17:40                 ` Davidlohr Bueso [this message]
2017-06-29 17:57                   ` Linus Torvalds
2017-06-29 18:33                     ` Davidlohr Bueso
     [not found]                       ` <20170629183339.GD3954-3dK4OQgjB4rH06JGZaSw0A@public.gmane.org>
2017-06-29 18:59                         ` Linus Torvalds
     [not found]                           ` <CA+55aFz8Mhx+A-g-5yOG-O1ZLRUR_fpeeA4iBNGH8EnDBZEdpA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-06-29 19:40                             ` Luis R. Rodriguez
2017-06-29 19:44                               ` Luis R. Rodriguez
     [not found]                                 ` <20170629194455.GR21846-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2017-06-29 20:58                                   ` Jakub Kicinski
2017-06-29 22:50                                     ` Luis R. Rodriguez
2017-06-29 22:53                                       ` Jakub Kicinski
2017-06-29 23:00                                         ` Luis R. Rodriguez
2017-06-29 23:06                                           ` Jakub Kicinski
     [not found]                                       ` <20170629225003.GU21846-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2017-07-12 21:33                                         ` Luis R. Rodriguez
     [not found]                               ` <20170629194015.GQ21846-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2017-06-29 20:57                                 ` Linus Torvalds
2017-07-05  2:06                       ` Davidlohr Bueso
     [not found]                         ` <20170705020635.GD11168-3dK4OQgjB4rH06JGZaSw0A@public.gmane.org>
2017-07-07 19:58                           ` Linus Torvalds
2017-07-07 22:27                             ` Davidlohr Bueso
2017-07-07 22:48                               ` Linus Torvalds
2017-06-29 19:15                 ` Marcelo Tosatti
     [not found]                   ` <20170629191506.GB12368-I4X2Mt4zSy4@public.gmane.org>
2017-06-30  4:03                     ` Linus Torvalds
2017-06-30 11:55                       ` Marcelo Tosatti
2017-06-30 11:57                       ` Marcelo Tosatti
2017-06-30 17:30                       ` Krister Johansen
2017-06-14 22:20 ` [PATCH 3/4] firmware: avoid invalid fallback aborts by using killable swait Luis R. Rodriguez
2017-06-14 22:20 ` [PATCH 4/4] firmware: send -EINTR on signal abort on fallback mechanism Luis R. Rodriguez
2017-06-15  7:49 ` [PATCH 0/4] firmware: fix fallback mechanism by ignoring SIGCHLD Martin Fuzzey
     [not found] ` <20170614222017.14653-1-mcgrof-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2017-06-26 21:19   ` Luis R. Rodriguez
2017-06-29 15:14   ` Greg KH
     [not found]     ` <20170629151442.GA4880-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-06-29 17:29       ` Luis R. Rodriguez

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