From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Williams Subject: [PATCH 4/4] isci: correct erroneous for_each_isci_host macro Date: Thu, 06 Feb 2014 12:23:20 -0800 Message-ID: <20140206202320.5227.69468.stgit@viggo.jf.intel.com> References: <20140206202151.5227.12582.stgit@viggo.jf.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140206202151.5227.12582.stgit@viggo.jf.intel.com> Sender: stable-owner@vger.kernel.org To: linux-scsi@vger.kernel.org Cc: dave.jiang@intel.com, Maciej Patelczyk , JBottomley@Parallels.com, artur.paszkiewicz@intel.com, lukasz.dorau@intel.com, stable@vger.kernel.org List-Id: linux-scsi@vger.kernel.org From: Lukasz Dorau In the first place, the loop 'for' in the macro 'for_each_isci_host' (drivers/scsi/isci/host.h:314) is incorrect, because it accesses the 3rd element of 2 element array. After the 2nd iteration it executes the instruction: ihost = to_pci_info(pdev)->hosts[2] (while the size of the 'hosts' array equals 2) and reads an out of range element. In the second place, this loop is incorrectly optimized by GCC v4.8 (see http://marc.info/?l=linux-kernel&m=138998871911336&w=2). As a result, on platforms with two SCU controllers, the loop is executed more times than it can be (for i=0,1 and 2). It causes kernel panic during entering the S3 state and the following oops after 'rmmod isci': BUG: unable to handle kernel NULL pointer dereference at (null) IP: [] __list_add+0x1b/0xc0 Oops: 0000 [#1] SMP RIP: 0010:[] [] __list_add+0x1b/0xc0 Call Trace: [] __mutex_lock_slowpath+0x114/0x1b0 [] mutex_lock+0x1f/0x30 [] sas_disable_events+0x1b/0x50 [libsas] [] sas_unregister_ha+0x18/0x60 [libsas] [] isci_unregister+0x1e/0x40 [isci] [] isci_pci_remove+0x5d/0x100 [isci] [] pci_device_remove+0x3b/0xb0 [] __device_release_driver+0x7f/0xf0 [] driver_detach+0xa8/0xb0 [] bus_remove_driver+0x9b/0x120 [] driver_unregister+0x2c/0x50 [] pci_unregister_driver+0x23/0x80 [] isci_exit+0x10/0x1e [isci] [] SyS_delete_module+0x16b/0x2d0 [] ? do_notify_resume+0x61/0xa0 [] system_call_fastpath+0x16/0x1b The loop has been corrected. This patch fixes kernel panic during entering the S3 state and the above oops. Signed-off-by: Lukasz Dorau Reviewed-by: Maciej Patelczyk Tested-by: Lukasz Dorau Cc: Dave Jiang Cc: Signed-off-by: Dan Williams --- drivers/scsi/isci/host.h | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/isci/host.h b/drivers/scsi/isci/host.h index 4911310a38f5..22a9bb1abae1 100644 --- a/drivers/scsi/isci/host.h +++ b/drivers/scsi/isci/host.h @@ -311,9 +311,8 @@ static inline struct Scsi_Host *to_shost(struct isci_host *ihost) } #define for_each_isci_host(id, ihost, pdev) \ - for (id = 0, ihost = to_pci_info(pdev)->hosts[id]; \ - id < ARRAY_SIZE(to_pci_info(pdev)->hosts) && ihost; \ - ihost = to_pci_info(pdev)->hosts[++id]) + for (id = 0; id < SCI_MAX_CONTROLLERS && \ + (ihost = to_pci_info(pdev)->hosts[id]); id++) static inline void wait_for_start(struct isci_host *ihost) {