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spi: fix race freeing dummy_tx/rx before it is unmapped

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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>
Cc: stable@vger.kernel.org
This commit is contained in:
Martin Sperl 2015-05-10 07:50:45 +00:00 committed by Mark Brown
parent f8bb820da4
commit 8e76ef88f6
1 changed files with 6 additions and 5 deletions
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11
drivers/spi/spi.c
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@ -988,9 +988,6 @@ void spi_finalize_current_message(struct spi_master *master)
spin_lock_irqsave(&master->queue_lock, flags); spin_lock_irqsave(&master->queue_lock, flags);
mesg = master->cur_msg; mesg = master->cur_msg;
master->cur_msg = NULL;
queue_kthread_work(&master->kworker, &master->pump_messages);
spin_unlock_irqrestore(&master->queue_lock, flags); spin_unlock_irqrestore(&master->queue_lock, flags);
spi_unmap_msg(master, mesg); spi_unmap_msg(master, mesg);
@ -1003,9 +1000,13 @@ 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; 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; mesg->state = NULL;
if (mesg->complete) if (mesg->complete)