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| author | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2014-03-04 02:22:35 +0400 |
|---|---|---|
| committer | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2014-12-10 22:53:20 +0300 |
| commit | 0765cbd3be699b4a72db67069247d514f06a1e4f (patch) | |
| tree | dd57c6f137bdfdb39d35d1b89241aa227726a213 | |
| parent | 0238507b951857360461b0635111e7376ffd44d1 (diff) | |
| download | linux-0765cbd3be699b4a72db67069247d514f06a1e4f.tar.xz | |
firewire: sbp2: protect a reference counter properly
The assertion in the comment in sbp2_allow_block() is no longer true.
Or maybe it never was true. At least now, the sole caller of
sbp2_allow_block(), sbp2_login, can run concurrently to one of
sbp2_unblock()'s callers, sbp2_remove.
sbp2_login is performed by sbp2_logical_unit.work.
sbp2_remove is performed by fw_device.work.
sbp2_remove cancels sbp2_logical_unit.work, but only after it called
sbp2_unblock.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
| -rw-r--r-- | drivers/firewire/sbp2.c | 14 |
1 files changed, 6 insertions, 8 deletions
diff --git a/drivers/firewire/sbp2.c b/drivers/firewire/sbp2.c index 7aef911fdc71..c7fc78c23978 100644 --- a/drivers/firewire/sbp2.c +++ b/drivers/firewire/sbp2.c @@ -689,14 +689,12 @@ static void sbp2_agent_reset_no_wait(struct sbp2_logical_unit *lu) static inline void sbp2_allow_block(struct sbp2_logical_unit *lu) { - /* - * We may access dont_block without taking card->lock here: - * All callers of sbp2_allow_block() and all callers of sbp2_unblock() - * are currently serialized against each other. - * And a wrong result in sbp2_conditionally_block()'s access of - * dont_block is rather harmless, it simply misses its first chance. - */ - --lu->tgt->dont_block; + struct sbp2_target *tgt = lu->tgt; + struct fw_card *card = target_parent_device(tgt)->card; + + spin_lock_irq(&card->lock); + --tgt->dont_block; + spin_unlock_irq(&card->lock); } /* |