Commit 762877485 "mmc: core: Handle card shutdown from mmc_bus"
added shutdown support. However, there are some situations where the
'owner' struct pointer can be NULL.
Solve this by adding a check, just as it's done in the other busses.
This commit solves a panic upon a reboot request, found in today's linux-next,
on a Armada 370 Mirabox board.
[snip]
[ 225.592003] Unable to handle kernel NULL pointer dereference at virtual address 0000004c
[ 225.600114] pgd = eea2c000
[ 225.602897] [0000004c] *pgd=2ea38831, *pte=00000000, *ppte=00000000
[ 225.609216] Internal error: Oops: 17 [#1] PREEMPT SMP ARM
[ 225.614628] CPU: 0 PID: 1100 Comm: init Not tainted 3.10.0-next-20130704 #19
[ 225.621690] task: ef1adb00 ti: ef3ce000 task.ti: ef3ce000
[ 225.627111] PC is at mmc_bus_shutdown+0x14/0x5c
[ 225.631657] LR is at device_shutdown+0x34/0x184
[ 225.636196] pc : [<c0267548>] lr : [<c01b487c>] psr: 600f0013
[ 225.636196] sp : ef3cfe68 ip : 00000002 fp : 00000000
[ 225.647693] r10: 00000000 r9 : ef3ce000 r8 : c049229c
[ 225.652927] r7 : ef304c3c r6 : c04b4f30 r5 : ef304c08 r4 : ef304000
[ 225.659466] r3 : ef304c08 r2 : 00000000 r1 : 00000000 r0 : ef304c00
[ 225.666005] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
[ 225.673153] Control: 10c5387d Table: 2ea2c019 DAC: 00000015
[ 225.678909] Process init (pid: 1100, stack limit = 0xef3ce238)
Cc: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Cc: Chris Ball <cjb@xxxxxxxxxx>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
---
This patch applies cleanly on today's linux-next.
Honestly, I can't see how the owner pointer can be NULL,
but every other bus driver is checking, so I guess it can
be NULL under some circumstance.
drivers/mmc/core/bus.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/mmc/core/bus.c b/drivers/mmc/core/bus.c
index b9e5bea..8fcf0b9 100644
--- a/drivers/mmc/core/bus.c
+++ b/drivers/mmc/core/bus.c
@@ -129,7 +129,8 @@ static void mmc_bus_shutdown(struct device *dev)
struct mmc_host *host = card->host;
int ret;
- drv->shutdown(card);
+ if (drv)
+ drv->shutdown(card);
if (host->bus_ops->shutdown) {
ret = host->bus_ops->shutdown(host);
--
1.8.1.5
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