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| author | Greg Banks <gnb@melbourne.sgi.com> | 2006-10-02 02:17:57 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-02 07:57:19 -0700 |
| commit | c081a0c7cfe42adf8e8b9c2b8d0b2ec7f47603e8 (patch) | |
| tree | b8be50680c576427f29195946332bacd56eb1055 /net/sunrpc | |
| parent | 5685f0fa1c24b138d041ef129ed419c5effa40e1 (diff) | |
| download | blackbird-obmc-linux-c081a0c7cfe42adf8e8b9c2b8d0b2ec7f47603e8.tar.gz blackbird-obmc-linux-c081a0c7cfe42adf8e8b9c2b8d0b2ec7f47603e8.zip | |
[PATCH] knfsd: test and set SK_BUSY atomically
The SK_BUSY bit in svc_sock->sk_flags ensures that we do not attempt to
enqueue a socket twice. Currently, setting and clearing the bit is protected
by svc_serv->sv_lock. As I intend to reduce the data that the lock protects
so it's not held when svc_sock_enqueue() tests and sets SK_BUSY, that test and
set needs to be atomic.
Signed-off-by: Greg Banks <gnb@melbourne.sgi.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'net/sunrpc')
| -rw-r--r-- | net/sunrpc/svcsock.c | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c index 88b51c4ecb8b..a38df4589ae9 100644 --- a/net/sunrpc/svcsock.c +++ b/net/sunrpc/svcsock.c @@ -46,14 +46,13 @@ /* SMP locking strategy: * - * svc_serv->sv_lock protects most stuff for that service. + * svc_serv->sv_lock protects most stuff for that service. * svc_sock->sk_defer_lock protects the svc_sock->sk_deferred list + * svc_sock->sk_flags.SK_BUSY prevents a svc_sock being enqueued multiply. * * Some flags can be set to certain values at any time * providing that certain rules are followed: * - * SK_BUSY can be set to 0 at any time. - * svc_sock_enqueue must be called afterwards * SK_CONN, SK_DATA, can be set or cleared at any time. * after a set, svc_sock_enqueue must be called. * after a clear, the socket must be read/accepted @@ -170,8 +169,13 @@ svc_sock_enqueue(struct svc_sock *svsk) goto out_unlock; } - if (test_bit(SK_BUSY, &svsk->sk_flags)) { - /* Don't enqueue socket while daemon is receiving */ + /* Mark socket as busy. It will remain in this state until the + * server has processed all pending data and put the socket back + * on the idle list. We update SK_BUSY atomically because + * it also guards against trying to enqueue the svc_sock twice. + */ + if (test_and_set_bit(SK_BUSY, &svsk->sk_flags)) { + /* Don't enqueue socket while already enqueued */ dprintk("svc: socket %p busy, not enqueued\n", svsk->sk_sk); goto out_unlock; } @@ -185,15 +189,11 @@ svc_sock_enqueue(struct svc_sock *svsk) dprintk("svc: socket %p no space, %d*2 > %ld, not enqueued\n", svsk->sk_sk, atomic_read(&svsk->sk_reserved)+serv->sv_bufsz, svc_sock_wspace(svsk)); + clear_bit(SK_BUSY, &svsk->sk_flags); goto out_unlock; } clear_bit(SOCK_NOSPACE, &svsk->sk_sock->flags); - /* Mark socket as busy. It will remain in this state until the - * server has processed all pending data and put the socket back - * on the idle list. - */ - set_bit(SK_BUSY, &svsk->sk_flags); if (!list_empty(&serv->sv_threads)) { rqstp = list_entry(serv->sv_threads.next, |
