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Use read/write locks in queue sequential cutoffs

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If user thread is preempted during tree/list update and another IO
is issued on the same CPU, the structure will be in undefined state.
This may result in hung tasks, if the tree stops being a tree and a loop exists -
tree search functions won't be able to end properly; or panics if a NULL value appears
suddenly in the preempted thread, after a null-check was already done.

Signed-off-by: Kozlowski Mateusz <mateusz.kozlowski@intel.com>
This commit is contained in:
Kozlowski Mateusz 2021-03-23 09:50:34 +01:00
parent e321497ecc
commit 365f4f0d19
1 changed files with 6 additions and 0 deletions
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6
src/ocf_seq_cutoff.c
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@ -204,9 +204,11 @@ bool ocf_core_seq_cutoff_check(ocf_core_t core, struct ocf_request *req)
return false;
}
env_rwlock_read_lock(&req->io_queue->seq_cutoff->lock);
result = ocf_core_seq_cutoff_base_check(req->io_queue->seq_cutoff,
req->byte_position, req->byte_length, req->rw,
threshold, &queue_stream);
env_rwlock_read_unlock(&req->io_queue->seq_cutoff->lock);
if (queue_stream)
return result;
@ -319,8 +321,10 @@ void ocf_core_seq_cutoff_update(ocf_core_t core, struct ocf_request *req)
return;
}
env_rwlock_write_lock(&req->io_queue->seq_cutoff->lock);
stream = ocf_core_seq_cutoff_base_update(req->io_queue->seq_cutoff,
req->byte_position, req->byte_length, req->rw, true);
env_rwlock_write_unlock(&req->io_queue->seq_cutoff->lock);
if (stream->bytes >= threshold)
promote = true;
@ -330,8 +334,10 @@ void ocf_core_seq_cutoff_update(ocf_core_t core, struct ocf_request *req)
if (promote) {
env_rwlock_write_lock(&core->seq_cutoff->lock);
env_rwlock_write_lock(&req->io_queue->seq_cutoff->lock);
ocf_core_seq_cutoff_base_promote(core->seq_cutoff,
req->io_queue->seq_cutoff, stream);
env_rwlock_write_unlock(&req->io_queue->seq_cutoff->lock);
env_rwlock_write_unlock(&core->seq_cutoff->lock);
}
}