From: Damien Le Moal damien.lemoal@wdc.com
[ Upstream commit cb551b8dc079d2ef189145782627c99cb68c0255 ]
In BRM_status_show(), if the condition "!ioc->is_warpdrive" tested on entry to the function is true, a "goto out" is called. This results in unlocking ioc->pci_access_mutex without this mutex lock being taken. This generates the following splat:
[ 1148.539883] mpt3sas_cm2: BRM_status_show: BRM attribute is only for warpdrive [ 1148.547184] [ 1148.548708] ===================================== [ 1148.553501] WARNING: bad unlock balance detected! [ 1148.558277] 5.8.0-rc3+ #827 Not tainted [ 1148.562183] ------------------------------------- [ 1148.566959] cat/5008 is trying to release lock (&ioc->pci_access_mutex) at: [ 1148.574035] [<ffffffffc070b7a3>] BRM_status_show+0xd3/0x100 [mpt3sas] [ 1148.580574] but there are no more locks to release! [ 1148.585524] [ 1148.585524] other info that might help us debug this: [ 1148.599624] 3 locks held by cat/5008: [ 1148.607085] #0: ffff92aea3e392c0 (&p->lock){+.+.}-{3:3}, at: seq_read+0x34/0x480 [ 1148.618509] #1: ffff922ef14c4888 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x2a/0xb0 [ 1148.630729] #2: ffff92aedb5d7310 (kn->active#224){.+.+}-{0:0}, at: kernfs_seq_start+0x32/0xb0 [ 1148.643347] [ 1148.643347] stack backtrace: [ 1148.655259] CPU: 73 PID: 5008 Comm: cat Not tainted 5.8.0-rc3+ #827 [ 1148.665309] Hardware name: HGST H4060-S/S2600STB, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019 [ 1148.678394] Call Trace: [ 1148.684750] dump_stack+0x78/0xa0 [ 1148.691802] lock_release.cold+0x45/0x4a [ 1148.699451] __mutex_unlock_slowpath+0x35/0x270 [ 1148.707675] BRM_status_show+0xd3/0x100 [mpt3sas] [ 1148.716092] dev_attr_show+0x19/0x40 [ 1148.723664] sysfs_kf_seq_show+0x87/0x100 [ 1148.731193] seq_read+0xbc/0x480 [ 1148.737882] vfs_read+0xa0/0x160 [ 1148.744514] ksys_read+0x58/0xd0 [ 1148.751129] do_syscall_64+0x4c/0xa0 [ 1148.757941] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 1148.766240] RIP: 0033:0x7f1230566542 [ 1148.772957] Code: Bad RIP value. [ 1148.779206] RSP: 002b:00007ffeac1bcac8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 1148.790063] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f1230566542 [ 1148.800284] RDX: 0000000000020000 RSI: 00007f1223460000 RDI: 0000000000000003 [ 1148.810474] RBP: 00007f1223460000 R08: 00007f122345f010 R09: 0000000000000000 [ 1148.820641] R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000000000 [ 1148.830728] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
Fix this by returning immediately instead of jumping to the out label.
Link: https://lore.kernel.org/r/20200701085254.51740-1-damien.lemoal@wdc.com Reviewed-by: Johannes Thumshirn johannes.thumshirn@wdc.com Acked-by: Sreekanth Reddy sreekanth.reddy@broadcom.com Signed-off-by: Damien Le Moal damien.lemoal@wdc.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/mpt3sas/mpt3sas_ctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/scsi/mpt3sas/mpt3sas_ctl.c b/drivers/scsi/mpt3sas/mpt3sas_ctl.c index b95f7d062ea44..82c4ecc16f191 100644 --- a/drivers/scsi/mpt3sas/mpt3sas_ctl.c +++ b/drivers/scsi/mpt3sas/mpt3sas_ctl.c @@ -2921,7 +2921,7 @@ BRM_status_show(struct device *cdev, struct device_attribute *attr, if (!ioc->is_warpdrive) { ioc_err(ioc, "%s: BRM attribute is only for warpdrive\n", __func__); - goto out; + return 0; } /* pci_access_mutex lock acquired by sysfs show path */ mutex_lock(&ioc->pci_access_mutex);