diff options
| author | Kuniyuki Iwashima <kuniyu@amazon.com> | 2024-04-01 20:31:25 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2024-04-04 05:27:13 +0300 |
| commit | 118f457da9ed58a79e24b73c2ef0aa1987241f0e (patch) | |
| tree | 6ab7e1a62a021dcff83f21f0e9b8935522ca6cdf /net/unix/garbage.c | |
| parent | 7c349ed090318b1c88a3e5dff3b24f732296edce (diff) | |
| download | linux-118f457da9ed58a79e24b73c2ef0aa1987241f0e.tar.xz | |
af_unix: Remove lock dance in unix_peek_fds().
In the previous GC implementation, the shape of the inflight socket
graph was not expected to change while GC was in progress.
MSG_PEEK was tricky because it could install inflight fd silently
and transform the graph.
Let's say we peeked a fd, which was a listening socket, and accept()ed
some embryo sockets from it. The garbage collection algorithm would
have been confused because the set of sockets visited in scan_inflight()
would change within the same GC invocation.
That's why we placed spin_lock(&unix_gc_lock) and spin_unlock() in
unix_peek_fds() with a fat comment.
In the new GC implementation, we no longer garbage-collect the socket
if it exists in another queue, that is, if it has a bridge to another
SCC. Also, accept() will require the lock if it has edges.
Thus, we need not do the complicated lock dance.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240401173125.92184-3-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/unix/garbage.c')
| -rw-r--r-- | net/unix/garbage.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/unix/garbage.c b/net/unix/garbage.c index 89ea71d9297b..12a4ec27e0d4 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -183,7 +183,7 @@ static void unix_free_vertices(struct scm_fp_list *fpl) } } -DEFINE_SPINLOCK(unix_gc_lock); +static DEFINE_SPINLOCK(unix_gc_lock); unsigned int unix_tot_inflight; void unix_add_edges(struct scm_fp_list *fpl, struct unix_sock *receiver) |