diff options
| -rw-r--r-- | sys/fs/fifofs/fifo_vnops.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/sys/fs/fifofs/fifo_vnops.c b/sys/fs/fifofs/fifo_vnops.c index c930d92..e339a8a 100644 --- a/sys/fs/fifofs/fifo_vnops.c +++ b/sys/fs/fifofs/fifo_vnops.c @@ -78,6 +78,10 @@ struct fileops fifo_ops_f = { /* * This structure is associated with the FIFO vnode and stores * the state associated with the FIFO. + * Notes about locking: + * - fi_readsock and fi_writesock are invariant since init time. + * - fi_readers and fi_writers are vnode lock protected. + * - fi_wgen is fif_mtx lock protected. */ struct fifoinfo { struct socket *fi_readsock; @@ -223,14 +227,9 @@ fail1: } /* - * General access to fi_readers and fi_writers is protected using - * the vnode lock. - * - * Protect the increment of fi_readers and fi_writers and the - * associated calls to wakeup() with the fifo mutex in addition - * to the vnode lock. This allows the vnode lock to be dropped - * for the msleep() calls below, and using the fifo mutex with - * msleep() prevents the wakeup from being missed. + * Use the fifo_mtx lock here, in addition to the vnode lock, + * in order to allow vnode lock dropping before msleep() calls + * and still avoiding missed wakeups. */ mtx_lock(&fifo_mtx); if (ap->a_mode & FREAD) { @@ -249,6 +248,8 @@ fail1: if (ap->a_mode & FWRITE) { if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) { mtx_unlock(&fifo_mtx); + if (fip->fi_writers == 0) + fifo_cleanup(vp); return (ENXIO); } fip->fi_writers++; |
