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| author |   Chandra Seetharaman <sekharan@us.ibm.com> | 2008-11-13 23:39:14 +0000 |
|---|---|---|
| committer |   Alasdair G Kergon <agk@redhat.com> | 2008-11-13 23:39:14 +0000 |
| commit | 8a57dfc6f943c92b861c9a19b0c86ddcb2aba768 (patch) | |
| tree | 18090d42e647cda854c93aa304cf03fbad44f6c0 /lib/dma-debug.c | |
| parent | dm: move pending queue wake_up end_io_acct (diff) | |
| download | linux-rng-8a57dfc6f943c92b861c9a19b0c86ddcb2aba768.tar.xz linux-rng-8a57dfc6f943c92b861c9a19b0c86ddcb2aba768.zip | |
dm: avoid destroying table in dm_any_congested
dm_any_congested() just checks for the DMF_BLOCK_IO and has no
code to make sure that suspend waits for dm_any_congested() to
complete. This patch adds such a check.
Without it, a race can occur with dm_table_put() attempting to
destroying the table in the wrong thread, the one running
dm_any_congested() which is meant to be quick and return
immediately.
Two examples of problems:
1. Sleeping functions called from congested code, the caller
of which holds a spin lock.
2. An ABBA deadlock between pdflush and multipathd. The two locks
in contention are inode lock and kernel lock.
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'lib/dma-debug.c')
0 files changed, 0 insertions, 0 deletions