jlaitine opened a new issue, #8346:
URL: https://github.com/apache/nuttx/issues/8346
It seems that several timeout functions have broken recently due to this
commit:
commit 1fb8c13e5e80ee4cd5758e76821378162451c2fa
Author: Xiang Xiao <xiaoxi...@xiaomi.com>
Date: Tue May 10 09:32:31 2022 +0800
Replace nxsem_timedwait_uninterruptible with
nxsem_tickwait_uninterruptible
Signed-off-by: Xiang Xiao <xiaoxi...@xiaomi.com>
For example: in net/utils/net_lock.c the change looks like this:
```
--- a/net/utils/net_lock.c
+++ b/net/utils/net_lock.c
@@ -97,27 +97,15 @@ _net_timedwait(sem_t *sem, bool interruptible, unsigned
int timeout)
if (timeout != UINT_MAX)
{
- struct timespec abstime;
-
- DEBUGVERIFY(clock_gettime(CLOCK_REALTIME, &abstime));
-
- abstime.tv_sec += timeout / MSEC_PER_SEC;
- abstime.tv_nsec += timeout % MSEC_PER_SEC * NSEC_PER_MSEC;
- if (abstime.tv_nsec >= NSEC_PER_SEC)
- {
- abstime.tv_sec++;
- abstime.tv_nsec -= NSEC_PER_SEC;
- }
-
/* Wait until we get the lock or until the timeout expires */
if (interruptible)
{
- ret = nxsem_timedwait(sem, &abstime);
+ ret = nxsem_tickwait(sem, MSEC2TICK(timeout));
}
else
{
- ret = nxsem_timedwait_uninterruptible(sem, &abstime);
+ ret = nxsem_tickwait_uninterruptible(sem, MSEC2TICK(timeout));
}
}
```
In the original code, the _net_timedwait alwas went to sleep if the timeout
is > 0. In the changed code, if MSEC2TICK(timeout) rounds to 0, the
nxsem_tickwait doesn't sleep at all.
I noticed this problem when i2c driver broke for stm32f7 board, and fixed
only this in PR #8303 . However, we are also experiencing some networking
problems, which may be due to the code above
There are several alternatives to fix this problem:
1)
In all of the places be changed into rounding up the MSEC2TICK / USEC2TICK
return value, for example "MSEC2TICK(timeout + (MSEC_PER_TICK / 2) - 1).
Pros:
- Doesn't break anything unknown
Cons:
- The rounding creeps in to almost everywhere where the macros are used
2)
We could change the functionality of MSEC2TIC/USEC2TICK to round up by
default (actually some OS's do this, see e..g linux jiffy calculation).
Pros:
- Cleanest code, fixes all the places at once
Cons:
- May affect off-tree/private code of nuttx users
- The functionality of current MSEC2TIC/USEC2TICK has been as it is since
90's
3)
We could revert the change
Pros:
-Fixes the original problem
Cons:
- The original change greatly simplifies the code
- Would probably lead to rebase problems
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