ata: fixes kernel crash while tracing ata_eh_link_autopsy event

[ Upstream commit f1601113ddc0339a745e702f4fb1ca37d4875e65 ]

When tracing ata link error event, the kernel crashes when the disk is
removed due to NULL pointer access by trace_ata_eh_link_autopsy API.
This occurs as the dev is NULL when the disk disappeared. This patch
fixes this crash by calling trace_ata_eh_link_autopsy only if "dev"
is not NULL.

v2 changes:
 Removed direct passing "link" pointer instead of "dev" in trace API.

Signed-off-by: Rameshwar Prasad Sahu <rsahu@apm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 255c03d15a29 ("libata: Add tracepoints")
Cc: stable@vger.kernel.org # v4.1+
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 5ab6fa9cfc2fff373767b2b564f8cb1c0d08b67e..5e8c07abf2e7ea5d2402a2879581bf9963a760f2 100644 (file)
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2237,8 +2237,8 @@ static void ata_eh_link_autopsy(struct ata_link *link)
                if (dev->flags & ATA_DFLAG_DUBIOUS_XFER)
                        eflags |= ATA_EFLAG_DUBIOUS_XFER;
                ehc->i.action |= ata_eh_speed_down(dev, eflags, all_err_mask);
+               trace_ata_eh_link_autopsy(dev, ehc->i.action, all_err_mask);
        }
-       trace_ata_eh_link_autopsy(dev, ehc->i.action, all_err_mask);
        DPRINTK("EXIT\n");
 }