gustavonihei commented on a change in pull request #4270:
URL: https://github.com/apache/incubator-nuttx/pull/4270#discussion_r682836365
##########
File path: libs/libc/time/lib_localtime.c
##########
@@ -2528,9 +2537,20 @@ void tzset(void)
{
FAR const char *name;
- tz_semtake(&g_lcl_sem);
-
name = getenv("TZ");
+ if (g_lcl_isset > 0 && name && strcmp(g_lcl_tzname, name) == 0)
+ {
+ return;
+ }
Review comment:
Honestly, I don't know.
The point I am having trouble to understand is why is the first check
needed, this one:
```c
if (g_lcl_isset > 0 && name && strcmp(g_lcl_tzname, name) == 0)
{
return;
}
```
In my mind right now there is the following question: Why isn't the fix just
the addition of the following check in the function entry:
```c
#ifndef __KERNEL__
if (up_interrupt_context())
{
return;
}
#endif
```
Because the code paths I am considering are:
1) If it's executing in interrupt context, the function will return either
by the first or by the second condition.
2) If it's executing in user/process context, it will check the global
variables twice, first without locking the semaphore (not thread-safe) and
second by locking the semaphore (thread-safe).
So, why is that unsafe check required at the function entry?
You confirmed before that is not for optimization purposes. So, for what
purpose is this?
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