From: Rusty Russell <rusty@rustcorp.com.au>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
linux-scsi <linux-scsi@vger.kernel.org>
Subject: Re: module: fix module_refcount() return when running in a module exit routine
Date: Mon, 19 Jan 2015 16:21:15 +1030 [thread overview]
Message-ID: <878ugzco8c.fsf@rustcorp.com.au> (raw)
In-Reply-To: <54BC93C3.7010808@hitachi.com>
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> writes:
> (2015/01/19 1:55), James Bottomley wrote:
>> From: James Bottomley <JBottomley@Parallels.com>
>>
>> After e513cc1 module: Remove stop_machine from module unloading,
>> module_refcount() is returning (unsigned long)-1 when called from within
>> a routine that runs in module_exit. This is confusing the scsi device
>> put code which is coded to detect a module_refcount() of zero for
>> running within a module exit routine and not try to do another
>> module_put. The fix is to restore the original behaviour of
>> module_refcount() and return zero if we're running inside an exit
>> routine.
>>
>> Fixes: e513cc1c07e2ab93a4514eec9833e031df3e30bb
>> Reported-by: Bart Van Assche <bvanassche@acm.org>
>> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
>>
>
> Yes, this should be fixed as you said, since it must return "unsigned long" value.
But there are only three non-module callers:
drivers/scsi/scsi.c:1012: if (module && module_refcount(module) != 0)
drivers/staging/lustre/lustre/obdclass/lu_object.c:1359: LINVRNT(module_refcount(key->lct_owner) > 0);
include/linux/module.h:447:unsigned long module_refcount(struct module *mod);
kernel/debug/kdb/kdb_main.c:2026: kdb_printf("%4ld ", module_refcount(mod));
kernel/module.c:775:unsigned long module_refcount(struct module *mod)
kernel/module.c:779:EXPORT_SYMBOL(module_refcount);
kernel/module.c:859: seq_printf(m, " %lu ", module_refcount(mod));
kernel/module.c:911: return sprintf(buffer, "%lu\n", module_refcount(mk->mod));
The first one I think should be eliminated, and the second one is simply
an assertion before calling module_put() (which should probably be
eliminated). The others are just printing information.
Cheers,
Rusty.
next prev parent reply other threads:[~2015-01-19 7:42 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-18 16:55 module: fix module_refcount() return when running in a module exit routine James Bottomley
2015-01-18 23:37 ` Rusty Russell
2015-01-19 5:18 ` Masami Hiramatsu
2015-01-19 5:51 ` Rusty Russell [this message]
2015-01-19 8:28 ` Christoph Hellwig
2015-01-19 16:07 ` James Bottomley
2015-01-19 16:08 ` James Bottomley
2015-01-20 0:45 ` Rusty Russell
2015-01-20 2:17 ` Masami Hiramatsu
2015-01-20 17:23 ` James Bottomley
2015-01-21 5:30 ` Rusty Russell
2015-01-22 16:50 ` Christoph Hellwig
2015-01-22 17:02 ` James Bottomley
2015-01-23 2:54 ` Rusty Russell
2015-01-23 13:17 ` Christoph Hellwig
2015-01-23 18:42 ` James Bottomley
2015-01-23 23:35 ` Rusty Russell
2015-01-26 17:16 ` Christoph Hellwig
2015-01-28 9:23 ` Bart Van Assche
2015-01-28 21:45 ` James Bottomley
2015-01-29 12:16 ` Bart Van Assche
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