diff options
author | Dr. David Alan Gilbert <dgilbert@redhat.com> | 2019-08-23 15:39:24 +0100 |
---|---|---|
committer | Dr. David Alan Gilbert <dgilbert@redhat.com> | 2020-01-23 16:41:37 +0000 |
commit | fe4c15798a48143dd6b1f58d2d3cad12206ce211 (patch) | |
tree | 6b4794b93ffcd1fddb901ea6744b16c1bc528572 /tools/virtiofsd/passthrough_ll.c | |
parent | 951b3120dbc971f08681e1d860360e4a1e638902 (diff) | |
download | qemu-fe4c15798a48143dd6b1f58d2d3cad12206ce211.zip qemu-fe4c15798a48143dd6b1f58d2d3cad12206ce211.tar.gz qemu-fe4c15798a48143dd6b1f58d2d3cad12206ce211.tar.bz2 |
virtiofsd: Convert lo_destroy to take the lo->mutex lock itself
lo_destroy was relying on some implicit knowledge of the locking;
we can avoid this if we create an unref_inode that doesn't take
the lock and then grab it for the whole of the lo_destroy.
Suggested-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Diffstat (limited to 'tools/virtiofsd/passthrough_ll.c')
-rw-r--r-- | tools/virtiofsd/passthrough_ll.c | 31 |
1 files changed, 17 insertions, 14 deletions
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index eb001b9..fc15d61 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -1344,14 +1344,13 @@ static void lo_unlink(fuse_req_t req, fuse_ino_t parent, const char *name) lo_inode_put(lo, &inode); } -static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inode, - uint64_t n) +/* To be called with lo->mutex held */ +static void unref_inode(struct lo_data *lo, struct lo_inode *inode, uint64_t n) { if (!inode) { return; } - pthread_mutex_lock(&lo->mutex); assert(inode->nlookup >= n); inode->nlookup -= n; if (!inode->nlookup) { @@ -1362,15 +1361,24 @@ static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inode, } g_hash_table_destroy(inode->posix_locks); pthread_mutex_destroy(&inode->plock_mutex); - pthread_mutex_unlock(&lo->mutex); /* Drop our refcount from lo_do_lookup() */ lo_inode_put(lo, &inode); - } else { - pthread_mutex_unlock(&lo->mutex); } } +static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inode, + uint64_t n) +{ + if (!inode) { + return; + } + + pthread_mutex_lock(&lo->mutex); + unref_inode(lo, inode, n); + pthread_mutex_unlock(&lo->mutex); +} + static void lo_forget_one(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup) { struct lo_data *lo = lo_data(req); @@ -2458,13 +2466,7 @@ static void lo_destroy(void *userdata) { struct lo_data *lo = (struct lo_data *)userdata; - /* - * Normally lo->mutex must be taken when traversing lo->inodes but - * lo_destroy() is a serialized request so no races are possible here. - * - * In addition, we cannot acquire lo->mutex since unref_inode() takes it - * too and this would result in a recursive lock. - */ + pthread_mutex_lock(&lo->mutex); while (true) { GHashTableIter iter; gpointer key, value; @@ -2475,8 +2477,9 @@ static void lo_destroy(void *userdata) } struct lo_inode *inode = value; - unref_inode_lolocked(lo, inode, inode->nlookup); + unref_inode(lo, inode, inode->nlookup); } + pthread_mutex_unlock(&lo->mutex); } static struct fuse_lowlevel_ops lo_oper = { |