diff options
author | Boqun Feng <boqun.feng@gmail.com> | 2020-08-07 15:42:33 +0800 |
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committer | Peter Zijlstra <peterz@infradead.org> | 2020-08-26 12:42:06 +0200 |
commit | f611e8cf98ec908b9c2c0da6064a660fc6022487 (patch) | |
tree | 4cd8ee925a3af4711d7a5060f7939e1b49f30325 /arch/x86/kernel | |
parent | d4f200e579e96051f1f081f795820787826eb234 (diff) |
lockdep: Take read/write status in consideration when generate chainkey
Currently, the chainkey of a lock chain is a hash sum of the class_idx
of all the held locks, the read/write status are not taken in to
consideration while generating the chainkey. This could result into a
problem, if we have:
P1()
{
read_lock(B);
lock(A);
}
P2()
{
lock(A);
read_lock(B);
}
P3()
{
lock(A);
write_lock(B);
}
, and P1(), P2(), P3() run one by one. And when running P2(), lockdep
detects such a lock chain A -> B is not a deadlock, then it's added in
the chain cache, and then when running P3(), even if it's a deadlock, we
could miss it because of the hit of chain cache. This could be confirmed
by self testcase "chain cached mixed R-L/L-W ".
To resolve this, we use concept "hlock_id" to generate the chainkey, the
hlock_id is a tuple (hlock->class_idx, hlock->read), which fits in a u16
type. With this, the chainkeys are different is the lock sequences have
the same locks but different read/write status.
Besides, since we use "hlock_id" to generate chainkeys, the chain_hlocks
array now store the "hlock_id"s rather than lock_class indexes.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200807074238.1632519-15-boqun.feng@gmail.com
Diffstat (limited to 'arch/x86/kernel')
0 files changed, 0 insertions, 0 deletions