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Applying InnoDB snashot 5.0-ss4900 part 1, Fixes BUG#42279

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1) BUG#42279 - Race condition in btr_search_drop_page_hash_when_freed()

Detailed revision comments:

r4031 | marko | 2009-01-23 15:33:46 +0200 (Fri, 23 Jan 2009) | 8 lines
branches/5.0: btr_search_drop_page_hash_when_freed(): Check if
buf_page_get_gen() returns NULL.  The page may have been evicted
from the buffer pool between buf_page_peek_if_search_hashed() and
buf_page_get_gen(), because the buffer pool mutex will be released
between these two calls. (Bug #42279)

rb://82 approved by Heikki Tuuri
This commit is contained in:
Satya B 2009-04-24 17:18:20 +05:30
parent 55533a7efd
commit 0e4caf39fe
1 changed files with 10 additions and 2 deletions
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12
innobase/btr/btr0sea.c
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@ -1101,12 +1101,20 @@ btr_search_drop_page_hash_when_freed(
page = buf_page_get_gen(space, page_no, RW_S_LATCH, NULL,
BUF_GET_IF_IN_POOL, __FILE__, __LINE__,
&mtr);
/* Because the buffer pool mutex was released by
buf_page_peek_if_search_hashed(), it is possible that the
block was removed from the buffer pool by another thread
before buf_page_get_gen() got a chance to acquire the buffer
pool mutex again. Thus, we must check for a NULL return. */
if (UNIV_LIKELY(page != NULL)) {
#ifdef UNIV_SYNC_DEBUG
buf_page_dbg_add_level(page, SYNC_TREE_NODE_FROM_HASH);
buf_page_dbg_add_level(page, SYNC_TREE_NODE_FROM_HASH);
#endif /* UNIV_SYNC_DEBUG */
btr_search_drop_page_hash_index(page);
btr_search_drop_page_hash_index(page);
}
mtr_commit(&mtr);
}