| From | Kamal Mostafa <> | Subject | [PATCH 3.19.y-ckt 029/251] spi: fix race freeing dummy_tx/rx before it is unmapped | Date | Wed, 15 Jul 2015 18:05:50 -0700 |
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3.19.8-ckt4 -stable review patch. If anyone has any objections, please let me know.
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From: Martin Sperl <kernel@martin.sperl.org>
commit 8e76ef88f607174082023f50b87fe12dcdbe5db5 upstream.
Fix a race (with some kernel configurations) where a queued master->pump_messages runs and frees dummy_tx/rx before spi_unmap_msg is running (or is finished).
This results in the following messages: BUG: Bad page state in process page:db7ba030 count:0 mapcount:0 mapping: (null) index:0x0 flags: 0x200(arch_1) page dumped because: PAGE_FLAGS_CHECK_AT_PREP flag set ...
Reported-by: Noralf Trønnes <noralf@tronnes.org> Suggested-by: Noralf Trønnes <noralf@tronnes.org> Tested-by: Noralf Trønnes <noralf@tronnes.org> Signed-off-by: Martin Sperl <kernel@martin.sperl.org> Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/spi/spi.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index a17f533..bfa47d5 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1059,9 +1059,6 @@ void spi_finalize_current_message(struct spi_master *master) spin_lock_irqsave(&master->queue_lock, flags); mesg = master->cur_msg; - master->cur_msg = NULL; - - queue_kthread_work(&master->kworker, &master->pump_messages); spin_unlock_irqrestore(&master->queue_lock, flags); spi_unmap_msg(master, mesg); @@ -1074,9 +1071,13 @@ void spi_finalize_current_message(struct spi_master *master) } } - trace_spi_message_done(mesg); - + spin_lock_irqsave(&master->queue_lock, flags); + master->cur_msg = NULL; master->cur_msg_prepared = false; + queue_kthread_work(&master->kworker, &master->pump_messages); + spin_unlock_irqrestore(&master->queue_lock, flags); + + trace_spi_message_done(mesg); mesg->state = NULL; if (mesg->complete) -- 1.9.1
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