From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: [patch for 2.6.32? 1/3] scsi_lib.c: avoid calling scsi_device_put() from under ->host_lock Date: Tue, 17 Nov 2009 14:10:10 -0800 Message-ID: <200911172210.nAHMAAYJ014147@imap1.linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:50365 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752014AbZKQWKX (ORCPT ); Tue, 17 Nov 2009 17:10:23 -0500 Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James.Bottomley@HansenPartnership.com Cc: linux-scsi@vger.kernel.org, akpm@linux-foundation.org, strakh@ispras.ru, jens.axboe@oracle.com From: Alexander Strakh Driver scsi_lib.c might sleep in atomic context, because it calls scsi_device_put under spin_lock_irqsave. drivers/scsi/scsi_lib.c:356: spin_lock_irqsave(shost->host_lock, flags); scsi_device_put(sdev); Path to might_sleep macro from scsi_device_put: 1. scsi_device_put calls put_device at ./drivers/scsi/scsi.c:1111 2. put_device calls kobject_put at ./drivers/base/core.c:1038 3. kobject_put calls kref_put at ./lib/kobject.c 4. kref_put may call callback function kobject_release at ./lib/kref.c if refcount becomes zero, which might_sleep because it calls user event. Details: 4.1 kobject_cleanup calls kobject_uevent at ./lib/kobject.c:555 4.2 kobject_uevent calls kobject_uevent_env at ./lib/kobject_uevent.c:282 4.3 kobject_uevent_env calls call_usermodehelper_exec at ./include/linux/kmod.h:83 4.4 call_usermodehelper_exec calls wait_for_completion at ./kernel/kmod.c:481 4.5 wait_for_completion calls wait_for_common at ./kernel/sched.c:5710 4.5 wait_for_common calls might_sleep at ./kernels/sched.c:5692 Found by Linux Driver Verification project. Delete wrong sleeping function calls. Signed-off-by: Alexander Strakh Cc: James Bottomley Cc: Jens Axboe Signed-off-by: Andrew Morton --- drivers/scsi/scsi_lib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN drivers/scsi/scsi_lib.c~scsi_libc-avoid-calling-scsi_device_put-from-under-host_lock drivers/scsi/scsi_lib.c --- a/drivers/scsi/scsi_lib.c~scsi_libc-avoid-calling-scsi_device_put-from-under-host_lock +++ a/drivers/scsi/scsi_lib.c @@ -353,9 +353,9 @@ static void scsi_single_lun_run(struct s spin_unlock_irqrestore(shost->host_lock, flags); blk_run_queue(sdev->request_queue); - spin_lock_irqsave(shost->host_lock, flags); scsi_device_put(sdev); + spin_lock_irqsave(shost->host_lock, flags); } out: spin_unlock_irqrestore(shost->host_lock, flags); _