diff options
Diffstat (limited to 'sys/kern/sys_pipe.c')
| -rw-r--r-- | sys/kern/sys_pipe.c | 78 |
1 files changed, 54 insertions, 24 deletions
diff --git a/sys/kern/sys_pipe.c b/sys/kern/sys_pipe.c index 034d7937932..5586bab538f 100644 --- a/sys/kern/sys_pipe.c +++ b/sys/kern/sys_pipe.c @@ -1,4 +1,4 @@ -/* $OpenBSD: sys_pipe.c,v 1.99 2019/11/19 19:19:28 anton Exp $ */ +/* $OpenBSD: sys_pipe.c,v 1.100 2019/11/29 15:15:10 anton Exp $ */ /* * Copyright (c) 1996 John S. Dyson @@ -96,6 +96,11 @@ static unsigned int amountpipekva; struct pool pipe_pool; +/* + * Global lock protecting fields of `struct pipe'. + */ +struct rwlock pipe_lock = RWLOCK_INITIALIZER("pipeglk"); + int dopipe(struct proc *, int *, int); int pipelock(struct pipe *); void pipeunlock(struct pipe *); @@ -103,6 +108,7 @@ void pipeselwakeup(struct pipe *); struct pipe *pipe_create(void); void pipe_destroy(struct pipe *); +int pipe_rundown(struct pipe *); int pipe_buffer_realloc(struct pipe *, u_int); void pipe_buffer_free(struct pipe *); @@ -335,11 +341,19 @@ pipe_read(struct file *fp, struct uio *uio, int fflags) KERNEL_LOCK(); - error = pipelock(rpipe); - if (error) - goto done; - + rw_enter_write(&pipe_lock); ++rpipe->pipe_busy; + rw_exit_write(&pipe_lock); + + error = pipelock(rpipe); + if (error) { + rw_enter_write(&pipe_lock); + --rpipe->pipe_busy; + pipe_rundown(rpipe); + rw_exit_write(&pipe_lock); + KERNEL_UNLOCK(); + return (error); + } while (uio->uio_resid) { /* @@ -415,15 +429,11 @@ pipe_read(struct file *fp, struct uio *uio, int fflags) if (error == 0) getnanotime(&rpipe->pipe_atime); unlocked_error: + rw_enter_write(&pipe_lock); + --rpipe->pipe_busy; - /* - * PIPE_WANTD processing only makes sense if pipe_busy is 0. - */ - if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANTD)) { - rpipe->pipe_state &= ~(PIPE_WANTD|PIPE_WANTW); - wakeup(rpipe); - } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { + if (pipe_rundown(rpipe) == 0 && rpipe->pipe_buffer.cnt < MINPIPESIZE) { /* * Handle write blocking hysteresis. */ @@ -433,10 +443,11 @@ unlocked_error: } } + rw_exit_write(&pipe_lock); + if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) pipeselwakeup(rpipe); -done: KERNEL_UNLOCK(); return (error); } @@ -461,17 +472,16 @@ pipe_write(struct file *fp, struct uio *uio, int fflags) return (EPIPE); } + rw_enter_write(&pipe_lock); ++wpipe->pipe_busy; + rw_exit_write(&pipe_lock); error = pipelock(wpipe); if (error) { - /* Failed to acquire lock, wakeup if run-down can proceed. */ + rw_enter_write(&pipe_lock); --wpipe->pipe_busy; - if ((wpipe->pipe_busy == 0) && - (wpipe->pipe_state & PIPE_WANTD)) { - wpipe->pipe_state &= ~(PIPE_WANTD | PIPE_WANTR); - wakeup(wpipe); - } + pipe_rundown(wpipe); + rw_exit_write(&pipe_lock); KERNEL_UNLOCK(); return (error); } @@ -612,12 +622,11 @@ pipe_write(struct file *fp, struct uio *uio, int fflags) pipeunlock(wpipe); unlocked_error: + rw_enter_write(&pipe_lock); + --wpipe->pipe_busy; - if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANTD)) { - wpipe->pipe_state &= ~(PIPE_WANTD | PIPE_WANTR); - wakeup(wpipe); - } else if (wpipe->pipe_buffer.cnt > 0) { + if (pipe_rundown(wpipe) == 0 && wpipe->pipe_buffer.cnt > 0) { /* * If we have put any characters in the buffer, we wake up * the reader. @@ -628,6 +637,8 @@ unlocked_error: } } + rw_exit_write(&pipe_lock); + /* * Don't return EPIPE if I/O was successful */ @@ -810,11 +821,13 @@ pipe_destroy(struct pipe *cpipe) * we want to close it down. */ cpipe->pipe_state |= PIPE_EOF; + rw_enter_write(&pipe_lock); while (cpipe->pipe_busy) { wakeup(cpipe); cpipe->pipe_state |= PIPE_WANTD; - tsleep(cpipe, PRIBIO, "pipecl", 0); + rwsleep_nsec(cpipe, &pipe_lock, PRIBIO, "pipecl", INFSLP); } + rw_exit_write(&pipe_lock); /* * Disconnect from peer @@ -834,6 +847,23 @@ pipe_destroy(struct pipe *cpipe) pool_put(&pipe_pool, cpipe); } +/* + * Returns non-zero if a rundown is currently ongoing. + */ +int +pipe_rundown(struct pipe *cpipe) +{ + rw_assert_wrlock(&pipe_lock); + + if (cpipe->pipe_busy > 0 || (cpipe->pipe_state & PIPE_WANTD) == 0) + return (0); + + /* Only wakeup pipe_destroy() once the pipe is no longer busy. */ + cpipe->pipe_state &= ~(PIPE_WANTD | PIPE_WANTR | PIPE_WANTW); + wakeup(cpipe); + return (1); +} + int pipe_kqfilter(struct file *fp, struct knote *kn) { |