The state tracking of Linux tasks queue on xnpipe events was fairly broken. An easy way to corrupt some xnpipe_state_t object was to kill a Linux task blocked on opening a /dev/rtpX device (this left the state object queued in xnpipe_sleep, and hell broke loose on next queuing).
Another problem that popped up after reworking xnpipe queuing was a
stalled XNPIPE_USER_CONN after receiving a signal in xnpipe_open.
The following patch addresses both issues, appears to run fine so far
(at least the test case no longer triggers), and also cleans up some
redundant nklock acquisitions/releases. Nevertheless, I may miss some
corner case that might have triggered the original design. So please
check carefully.
Jan
---
ksrc/nucleus/pipe.c | 64 +++++++++++++++++++---------------------------------
1 file changed, 24 insertions(+), 40 deletions(-)
Index: b/ksrc/nucleus/pipe.c
===================================================================
--- a/ksrc/nucleus/pipe.c
+++ b/ksrc/nucleus/pipe.c
@@ -88,38 +88,39 @@ static inline void xnpipe_minor_free(int
static inline void xnpipe_enqueue_wait(xnpipe_state_t *state, int mask)
{
- spl_t s;
-
- xnlock_get_irqsave(&nklock, s);
-
if (state->wcount++ == 0)
appendq(&xnpipe_sleepq, &state->slink);
__setbits(state->status, mask);
+}
- xnlock_put_irqrestore(&nklock, s);
+static inline void xnpipe_dequeue_wait(xnpipe_state_t *state, int mask)
+{
+ if (testbits(state->status, mask)) {
+ if (--state->wcount == 0)
+ removeq(&xnpipe_sleepq, &state->slink);
+ __clrbits(state->status, mask);
+ }
}
/* Must be entered with nklock held. */
-#define xnpipe_wait(__state, __mask, __s, __cond) \
-({ \
- wait_queue_head_t *__waitq; \
- DEFINE_WAIT(__wait); \
- int __sigpending; \
- \
- if ((__mask) & XNPIPE_USER_WREAD) \
- __waitq = &(__state)->readq; \
- else \
- __waitq = &(__state)->syncq; \
- \
- xnpipe_enqueue_wait(__state, __mask); \
- xnlock_put_irqrestore(&nklock, __s); \
+#define xnpipe_wait(__state, __mask, __s, __cond) \
+({ \
+ wait_queue_head_t *__waitq; \
+ DEFINE_WAIT(__wait); \
+ int __sigpending; \
+ \
+ if ((__mask) & XNPIPE_USER_WREAD) \
+ __waitq = &(__state)->readq; \
+ else \
+ __waitq = &(__state)->syncq; \
+ \
+ xnpipe_enqueue_wait(__state, __mask); \
+ xnlock_put_irqrestore(&nklock, __s); \
\
prepare_to_wait_exclusive(__waitq, &__wait, TASK_INTERRUPTIBLE);\
\
- if (__cond) \
- xnpipe_dequeue_wait(__state, __mask); \
- else \
+ if (!__cond) \
schedule(); \
\
finish_wait(__waitq, &__wait); \
@@ -127,25 +128,11 @@ static inline void xnpipe_enqueue_wait(x
\
/* Restore the interrupt state initially set by the caller. */ \
xnlock_get_irqsave(&nklock, __s); \
+ xnpipe_dequeue_wait(__state, __mask); \
\
__sigpending; \
})
-static inline void xnpipe_dequeue_wait(xnpipe_state_t *state, int mask)
-{
- spl_t s;
-
- xnlock_get_irqsave(&nklock, s);
-
- if (testbits(state->status, mask)) {
- if (--state->wcount == 0)
- removeq(&xnpipe_sleepq, &state->slink);
- __clrbits(state->status, mask);
- }
-
- xnlock_put_irqrestore(&nklock, s);
-}
-
static void xnpipe_wakeup_proc(void *cookie)
{
xnholder_t *holder, *nholder;
@@ -168,7 +155,6 @@ static void xnpipe_wakeup_proc(void *coo
before calling wake_up_interruptible(). */
if ((rbits & XNPIPE_USER_WREAD_READY) != 0) {
if (waitqueue_active(&state->readq)) {
- xnpipe_dequeue_wait(state,
XNPIPE_USER_WREAD);
xnlock_put_irqrestore(&nklock, s);
wake_up_interruptible(&state->readq);
rbits &= ~XNPIPE_USER_WREAD_READY;
@@ -177,7 +163,6 @@ static void xnpipe_wakeup_proc(void *coo
}
if ((rbits & XNPIPE_USER_WSYNC_READY) != 0) {
if (waitqueue_active(&state->syncq)) {
- xnpipe_dequeue_wait(state,
XNPIPE_USER_WSYNC);
xnlock_put_irqrestore(&nklock, s);
wake_up_interruptible(&state->syncq);
rbits &= ~XNPIPE_USER_WSYNC_READY;
@@ -666,8 +651,7 @@ static int xnpipe_open(struct inode *ino
sigpending = xnpipe_wait(state, XNPIPE_USER_WREAD, s,
testbits(state->status,
XNPIPE_KERN_CONN));
if (sigpending) {
- if (!testbits(state->status, XNPIPE_KERN_CONN))
- xnpipe_cleanup_user_conn(state);
+ xnpipe_cleanup_user_conn(state);
xnlock_put_irqrestore(&nklock, s);
return -ERESTARTSYS;
}
signature.asc
Description: OpenPGP digital signature
_______________________________________________ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
