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| author | Peter Zijlstra | 2011-01-17 13:45:37 +0100 |
|---|---|---|
| committer | Ingo Molnar | 2011-01-18 15:10:35 +0100 |
| commit | c5ed5145591774bd9a2960ba4ca45a02fc70aad1 (patch) | |
| tree | f7e53164a33e1a0a41a4b3a7b508835361e39689 /crypto/cipher.c | |
| parent | perf tools: Fix tracepoint id to string perf.data header table (diff) | |
| download | kernel-qcow2-linux-c5ed5145591774bd9a2960ba4ca45a02fc70aad1.tar.gz kernel-qcow2-linux-c5ed5145591774bd9a2960ba4ca45a02fc70aad1.tar.xz kernel-qcow2-linux-c5ed5145591774bd9a2960ba4ca45a02fc70aad1.zip | |
perf: Fix contexted inheritance
Linus reported that the RCU lockdep annotation bits triggered for this
rcu_dereference() because we're not holding rcu_read_lock().
Going over the code I cannot convince myself its correct:
- holding a ref on the parent_ctx, doesn't avoid it being uncloned
concurrently (as the comment says), so we can race with a free.
- holding parent_ctx->mutex doesn't avoid the above free from taking
place either, it would at best avoid parent_ctx from being freed.
I.e. the warning is correct. To fix the bug, serialize against the
unclone_ctx() call by extending the reach of the parent_ctx->lock.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'crypto/cipher.c')
0 files changed, 0 insertions, 0 deletions