From: Brian King <brking@us.ibm.com>
To: Andrew Morton <akpm@osdl.org>
Cc: Greg KH <greg@kroah.com>,
linux-kernel@vger.kernel.org,
linux-hotplug-devel@lists.sourceforge.net
Subject: Re: [PATCH] call_usermodehelper hang
Date: Mon, 12 Apr 2004 10:25:49 -0500 [thread overview]
Message-ID: <407AB4FD.4070905@us.ibm.com> (raw)
In-Reply-To: 20040410131137.0eff0ae2.akpm@osdl.org
[-- Attachment #1: Type: text/plain, Size: 1065 bytes --]
Andrew Morton wrote:
> Greg KH <greg@kroah.com> wrote:
>
>>>The deadlock opportunity occurs during the call_usermodehelper() handoff to
>>
>> > keventd, which is synchronous.
>> >
>> > 2-3 years back I did have a call_usermodehelper() which was fully async.
>> > It was pretty unpleasant because of the need to atomically allocate
>> > arbitrary amounts of memory to hold the argv[] and endp[] arrays, to pass
>> > them between a couple of threads and to then correctly free it all up
>> > again.
>>
>> Ok, you've convinced me of the mess that would cause. So what should we
>> do to help fix this? Serialize call_usermodehelper()?
>
>
> May as well bring back call_usermodehelper_async() I guess.
>
>
> There are two patches here, and they are totally untested...
I loaded the patches on my ppc64 box and they worked fine after I fixed a compile
bug. The attached patch fixes the compile bug and changes the call_usermodehelper
call in kset_hotplug to call_usermodehelper_async.
-Brian
--
Brian King
eServer Storage I/O
IBM Linux Technology Center
[-- Attachment #2: call_usermodehelper_kobject.patch --]
[-- Type: text/plain, Size: 1253 bytes --]
Fixes a compile error in call_usermodehelper_async and changes kset_hotplug
to use call_usermodehelper_async, since it is called with a semaphore held,
which can result in a deadlock.
---
diff -puN kernel/kmod.c~call_usermodehelper_kobject kernel/kmod.c
--- linux-2.6.5/kernel/kmod.c~call_usermodehelper_kobject Mon Apr 12 08:27:20 2004
+++ linux-2.6.5-bjking1/kernel/kmod.c Mon Apr 12 08:27:44 2004
@@ -296,7 +296,7 @@ int call_usermodehelper_async(char *path
{
struct subprocess_info *sub_info;
- if (system_state != SYSTEM_RUNNING)
+ if (!system_running)
return -EBUSY;
if (path[0] == '\0')
goto out;
diff -puN lib/kobject.c~call_usermodehelper_kobject lib/kobject.c
--- linux-2.6.5/lib/kobject.c~call_usermodehelper_kobject Mon Apr 12 08:28:07 2004
+++ linux-2.6.5-bjking1/lib/kobject.c Mon Apr 12 08:28:28 2004
@@ -187,7 +187,7 @@ static void kset_hotplug(const char *act
pr_debug ("%s: %s %s %s %s %s %s %s\n", __FUNCTION__, argv[0], argv[1],
envp[0], envp[1], envp[2], envp[3], envp[4]);
- retval = call_usermodehelper (argv[0], argv, envp, 0);
+ retval = call_usermodehelper_async (argv[0], argv, envp, GFP_KERNEL);
if (retval)
pr_debug ("%s - call_usermodehelper returned %d\n",
__FUNCTION__, retval);
_
next prev parent reply other threads:[~2004-04-12 15:27 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-06 18:11 call_usermodehelper hang Brian King
2004-04-07 0:29 ` Andrew Morton
2004-04-07 6:11 ` Greg KH
2004-04-07 14:00 ` Brian King
2004-04-07 22:58 ` [PATCH] " Brian King
2004-04-08 22:47 ` Greg KH
2004-04-09 20:42 ` Brian King
2004-04-09 20:53 ` Greg KH
2004-04-09 21:05 ` Brian King
2004-04-09 21:15 ` Andrew Morton
2004-04-10 16:53 ` Greg KH
2004-04-10 20:11 ` Andrew Morton
2004-04-12 15:25 ` Brian King [this message]
2004-04-12 17:46 ` Andrew Morton
2004-04-16 17:55 ` Brian King
2004-04-12 18:49 ` Greg KH
2004-04-08 23:17 ` Chris Wright
2004-04-07 0:41 ` Chris Wright
2004-04-07 1:46 ` Brian King
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