On Sat, 11 Aug 2012, Bruce Evans wrote:
On Sat, 11 Aug 2012, David Xu wrote:
...
for (;;) {
if (!(uq->uq_flags & UQF_UMTXQ))
return (0);
- error = msleep(uq, &uc->uc_lock, PCATCH, wmesg,
- timo == NULL ? 0 : abs_timeout_gethz(timo));
- if (error != EWOULDBLOCK)
- break;
- umtxq_unlock(&uq->uq_key);
- if (abs_timeout_update(timo)) {
- error = ETIMEDOUT;
...
This follows the null pointer in abs_timeout_update() if timo == NULL.
timo == NULL has caused msleep to be called with a timeout of 0 ticks
(infinity), so EWOULDBLOCK should not normally be returned in this
case. However, I think it is always returned after the INT_MAX ticks
since a timeout of infinity is not really infinite, but just INT_MAX,
and there is no further magic for this value, so EWOULDBLOCK is
returned as usual if the timeout expires.
Oops, 0 really does mean infinity for msleep(), so there is no problem
unless it somehow returns EWOULDBLOCK.
...
+ abs_timeout_update(timo);
This still follows the null pointer, as above.
Still no problem.
Bruce
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