Haiku/haiku
Haiku/haiku
1
0
Fork 0
mirror of https://review.haiku-os.org/haiku synced 2024-11-23 07:18:40 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

kernel/block_cache: Minor code cleanup, and add a comment.

Browse Source 
Detailing how we avoid use-after-frees in get_cached_block when reads
fail.
This commit is contained in:
Augustin Cavalier 2024-11-19 18:14:29 -05:00
parent d8914ec8b0
commit 4550b3c025
1 changed files with 4 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
src/system/kernel/cache/block_cache.cpp vendored
View File

@ -1998,7 +1998,7 @@ mark_block_unbusy_reading(block_cache* cache, cached_block* block)
cache->busy_reading_count--; cache->busy_reading_count--;
if ((cache->busy_reading_waiters && cache->busy_reading_count == 0) if ((cache->busy_reading_waiters && cache->busy_reading_count == 0)
|| block->busy_reading_waiters) { || block->busy_reading_waiters) {
cache->busy_reading_waiters = false; cache->busy_reading_waiters = false;
block->busy_reading_waiters = false; block->busy_reading_waiters = false;
cache->busy_reading_condition.NotifyAll(); cache->busy_reading_condition.NotifyAll();
@ -2018,9 +2018,7 @@ wait_for_busy_reading_block(block_cache* cache, cached_block* block)
block->busy_reading_waiters = true; block->busy_reading_waiters = true;
mutex_unlock(&cache->lock); mutex_unlock(&cache->lock);
entry.Wait(); entry.Wait();
mutex_lock(&cache->lock); mutex_lock(&cache->lock);
} }
} }
@ -2038,9 +2036,7 @@ wait_for_busy_reading_blocks(block_cache* cache)
cache->busy_reading_waiters = true; cache->busy_reading_waiters = true;
mutex_unlock(&cache->lock); mutex_unlock(&cache->lock);
entry.Wait(); entry.Wait();
mutex_lock(&cache->lock); mutex_lock(&cache->lock);
} }
} }
@ -2058,9 +2054,7 @@ wait_for_busy_writing_block(block_cache* cache, cached_block* block)
block->busy_writing_waiters = true; block->busy_writing_waiters = true;
mutex_unlock(&cache->lock); mutex_unlock(&cache->lock);
entry.Wait(); entry.Wait();
mutex_lock(&cache->lock); mutex_lock(&cache->lock);
} }
} }
@ -2078,9 +2072,7 @@ wait_for_busy_writing_blocks(block_cache* cache)
cache->busy_writing_waiters = true; cache->busy_writing_waiters = true;
mutex_unlock(&cache->lock); mutex_unlock(&cache->lock);
entry.Wait(); entry.Wait();
mutex_lock(&cache->lock); mutex_lock(&cache->lock);
} }
} }
@ -2190,6 +2182,9 @@ retry:
} else if (block->busy_reading) { } else if (block->busy_reading) {
// The block is currently busy_reading - wait and try again later // The block is currently busy_reading - wait and try again later
wait_for_busy_reading_block(cache, block); wait_for_busy_reading_block(cache, block);
// The block may have been deleted or replaced in the meantime,
// so we must look it up in the hash again after waiting.
goto retry; goto retry;
} }