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Fix locking issue in blr_close_binlog

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In blr_open_binlog the refcnt increase of file which is already
open is protected by router->fileslock. In blr_close_binlog the
decrease of the refcnt was protected by file->lock.

This lead to a situation where it was possible that a file was
closed and the file instance freed, even though it just had been
taken into use by somebody else.

This is now fixed by solely using the router->fileslock for protecting
the increase and decrease of the refcnt.
This commit is contained in:
Johan Wikman
2015-11-25 23:42:05 +02:00
parent c167499c7b
commit e38334c457
1 changed files with 9 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
server/modules/routing/binlog/blr_file.c
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@ -643,11 +643,10 @@ struct stat statb;
void void
blr_close_binlog(ROUTER_INSTANCE *router, BLFILE *file) blr_close_binlog(ROUTER_INSTANCE *router, BLFILE *file)
{ {
spinlock_acquire(&file->lock); spinlock_acquire(&router->fileslock);
file->refcnt--; file->refcnt--;
if (file->refcnt == 0) if (file->refcnt == 0)
{ {
spinlock_acquire(&router->fileslock);
if (router->files == file) if (router->files == file)
router->files = file->next; router->files = file->next;
else else
@ -658,18 +657,18 @@ blr_close_binlog(ROUTER_INSTANCE *router, BLFILE *file)
if (ptr) if (ptr)
ptr->next = file->next; ptr->next = file->next;
} }
spinlock_release(&router->fileslock); }
else
{
file = NULL;
}
spinlock_release(&router->fileslock);
if (file)
{
close(file->fd); close(file->fd);
file->fd = -1; file->fd = -1;
}
if (file->refcnt == 0) {
spinlock_release(&file->lock);
free(file); free(file);
} else {
spinlock_release(&file->lock);
} }
} }