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From: Thiago Jung Bauermann <bauerman@linux.ibm.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Frederic Barrat <fbarrat@linux.ibm.com>,
	Andrew Donnellan <ajd@linux.ibm.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Jessica Yu <jeyu@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
	Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Michal Marek <michal.lkml@markovi.net>,
	linux-kbuild@vger.kernel.org,
	Masahiro Yamada <masahiroy@kernel.org>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	live-patching@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 04/13] module: use RCU to synchronize find_module
Date: Fri, 29 Jan 2021 18:29:43 -0300	[thread overview]
Message-ID: <871re31lfc.fsf@manicouagan.localdomain> (raw)
In-Reply-To: <20210129051012.GA2053@lst.de>


Christoph Hellwig <hch@lst.de> writes:

> On Thu, Jan 28, 2021 at 05:50:56PM -0300, Thiago Jung Bauermann wrote:
>> >  struct module *find_module(const char *name)
>> >  {
>> > -	module_assert_mutex();
>> 
>> Does it make sense to replace the assert above with the warn below (untested)?
>> 
>>      RCU_LOCKDEP_WARN(rcu_read_lock_sched_held());
>
> One caller actually holds module_mutex still.  And find_module_all,
> which implements the actual logic already asserts that either
> module_mutex is held or rcu_read_lock, so I don't tink we need an
> extra one here.

Ok, thanks for the clarification.

-- 
Thiago Jung Bauermann
IBM Linux Technology Center

WARNING: multiple messages have this Message-ID
From: Thiago Jung Bauermann <bauerman@linux.ibm.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Petr Mladek <pmladek@suse.com>, Jiri Kosina <jikos@kernel.org>,
	Andrew Donnellan <ajd@linux.ibm.com>,
	linux-kbuild@vger.kernel.org, David Airlie <airlied@linux.ie>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	linux-kernel@vger.kernel.org, Maxime Ripard <mripard@kernel.org>,
	live-patching@vger.kernel.org,
	Michal Marek <michal.lkml@markovi.net>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	dri-devel@lists.freedesktop.org,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Jessica Yu <jeyu@kernel.org>,
	Frederic Barrat <fbarrat@linux.ibm.com>,
	Daniel Vetter <daniel@ffwll.ch>, Miroslav Benes <mbenes@suse.cz>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 04/13] module: use RCU to synchronize find_module
Date: Fri, 29 Jan 2021 18:29:43 -0300	[thread overview]
Message-ID: <871re31lfc.fsf@manicouagan.localdomain> (raw)
In-Reply-To: <20210129051012.GA2053@lst.de>


Christoph Hellwig <hch@lst.de> writes:

> On Thu, Jan 28, 2021 at 05:50:56PM -0300, Thiago Jung Bauermann wrote:
>> >  struct module *find_module(const char *name)
>> >  {
>> > -	module_assert_mutex();
>> 
>> Does it make sense to replace the assert above with the warn below (untested)?
>> 
>>      RCU_LOCKDEP_WARN(rcu_read_lock_sched_held());
>
> One caller actually holds module_mutex still.  And find_module_all,
> which implements the actual logic already asserts that either
> module_mutex is held or rcu_read_lock, so I don't tink we need an
> extra one here.

Ok, thanks for the clarification.

-- 
Thiago Jung Bauermann
IBM Linux Technology Center

  reply	other threads:[~2021-01-29 21:31 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-28 18:14 module loader dead code removal and cleanups v2 Christoph Hellwig
2021-01-28 18:14 ` Christoph Hellwig
2021-01-28 18:14 ` [PATCH 01/13] powerpc/powernv: remove get_cxl_module Christoph Hellwig
2021-01-28 18:14   ` Christoph Hellwig
2021-01-28 18:14 ` [PATCH 02/13] drm: remove drm_fb_helper_modinit Christoph Hellwig
2021-02-03 10:34   ` Daniel Vetter
2021-02-03 10:34     ` Daniel Vetter
2021-02-03 10:34     ` Daniel Vetter
2021-02-03 10:49     ` Christoph Hellwig
2021-01-28 18:14 ` [PATCH 03/13] module: unexport find_module and module_mutex Christoph Hellwig
2021-01-28 18:14   ` Christoph Hellwig
2021-01-29 15:16   ` Miroslav Benes
2021-01-28 18:14 ` [PATCH 04/13] module: use RCU to synchronize find_module Christoph Hellwig
2021-01-28 18:14   ` Christoph Hellwig
2021-01-28 20:50   ` Thiago Jung Bauermann
2021-01-28 20:50     ` Thiago Jung Bauermann
2021-01-28 20:50     ` Thiago Jung Bauermann
2021-01-29  5:10     ` Christoph Hellwig
2021-01-29  5:10       ` Christoph Hellwig
2021-01-29 21:29       ` Thiago Jung Bauermann [this message]
2021-01-29 21:29         ` Thiago Jung Bauermann
2021-01-29 10:04   ` Petr Mladek
2021-01-29 10:04     ` Petr Mladek
2021-01-29 15:29   ` Miroslav Benes
2021-02-01 11:46     ` Christoph Hellwig
2021-02-01 11:46       ` Christoph Hellwig
2021-02-01 12:10     ` Jessica Yu
2021-02-01 12:10       ` Jessica Yu
2021-02-01 12:10       ` Jessica Yu
2021-02-01 13:16       ` Miroslav Benes
2021-02-01 13:16         ` Miroslav Benes
2021-02-01 13:16         ` Miroslav Benes
2021-01-28 18:14 ` [PATCH 05/13] kallsyms: refactor {,module_}kallsyms_on_each_symbol Christoph Hellwig
2021-01-29  9:43   ` Petr Mladek
2021-02-01 11:47     ` Christoph Hellwig
2021-02-01 11:47       ` Christoph Hellwig
2021-02-01 13:37       ` Miroslav Benes
2021-02-01 13:37         ` Miroslav Benes
2021-02-01 13:37         ` Miroslav Benes
2021-02-01 16:28         ` Christoph Hellwig
2021-02-01 16:28           ` Christoph Hellwig
2021-02-02 10:45           ` Miroslav Benes
2021-02-02 10:45             ` Miroslav Benes
2021-02-02 10:45             ` Miroslav Benes
2021-02-01 14:02   ` Miroslav Benes
2021-02-01 14:02     ` Miroslav Benes
2021-02-01 14:02     ` Miroslav Benes
2021-01-28 18:14 ` [PATCH 06/13] kallsyms: only build {, module_}kallsyms_on_each_symbol when required Christoph Hellwig
2021-01-28 18:14 ` [PATCH 07/13] module: mark module_mutex static Christoph Hellwig
2021-01-28 18:14   ` Christoph Hellwig
2021-01-28 18:14 ` [PATCH 08/13] module: remove each_symbol_in_section Christoph Hellwig
2021-01-28 18:14 ` [PATCH 09/13] module: merge each_symbol_section into find_symbol Christoph Hellwig
2021-01-28 18:14 ` [PATCH 10/13] module: pass struct find_symbol_args to find_symbol Christoph Hellwig
2021-01-28 18:14   ` Christoph Hellwig
2021-01-28 18:14 ` [PATCH 11/13] module: move struct symsearch to module.c Christoph Hellwig
2021-01-28 18:14   ` Christoph Hellwig
2021-01-28 18:14 ` [PATCH 12/13] module: remove EXPORT_SYMBOL_GPL_FUTURE Christoph Hellwig
2021-01-28 18:14   ` Christoph Hellwig
2021-01-28 18:14 ` [PATCH 13/13] module: remove EXPORT_UNUSED_SYMBOL* Christoph Hellwig
2021-02-02 12:13 module loader dead code removal and cleanups v3 Christoph Hellwig
2021-02-02 12:13 ` [PATCH 04/13] module: use RCU to synchronize find_module Christoph Hellwig
2021-02-02 12:13   ` Christoph Hellwig

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