nptl: Document AS-safe functions in cancellation.c.
Commit Message
In a recent conversation with Mathieu Desnoyer he pointed out that
because write is AS-safe all the wrappers around write should be
also AS-safe. We don't spell that out explicitly in the comments
for __pthread_enable_asynccancel and __pthread_disable_asynccancel
so I added them here.
OK for master?
8< --- 8< --- 8<
Document in comments that __pthread_enable_asynccancel and
__pthread_disable_asynccancel must be AS-safe in general with
the exception of the act of cancellation.
---
ChangeLog | 5 +++++
nptl/cancellation.c | 8 ++++++--
2 files changed, 11 insertions(+), 2 deletions(-)
Comments
On Fri, Oct 4, 2019 at 4:01 PM Carlos O'Donell <carlos@redhat.com> wrote:
>
> In a recent conversation with Mathieu Desnoyer he pointed out that
> because write is AS-safe all the wrappers around write should be
> also AS-safe. We don't spell that out explicitly in the comments
> for __pthread_enable_asynccancel and __pthread_disable_asynccancel
> so I added them here.
>
>
> /* The next two functions are similar to pthread_setcanceltype() but
> more specialized for the use in the cancelable functions like write().
> - They do not need to check parameters etc. */
> + They do not need to check parameters etc. This function must be
> + AS-safe, with the exception of the actual cancellation, because they
> + are called by wrappers around AS-safe functions like write().*/
Grammar nit: Either "_These functions_ must be AS-safe, ..." or
"because _it is_ called." The former is probably better because
consistent with the first sentence in this comment...
> -
> +/* This function must be AS-safe, with the exception of the actual
> + cancellation, because they are called by wrappers around AS-safe
> + functions like write().*/
... but then maybe you _don't_ want to add this comment as well.
zw
@@ -1,3 +1,8 @@
+2019-10-04 Carlos O'Donell <carlos@redhat.com>
+
+ * nptl/cancellation.c: Document that all functions here must be
+ AS-safe because they wrap AS-safe functions.
+
2019-10-03 Leandro Pereira <leandro.pereira@microsoft.com>
* elf/dl-load.c: Use __pread64_nocancel() instead of __lseek()+
@@ -24,7 +24,9 @@
/* The next two functions are similar to pthread_setcanceltype() but
more specialized for the use in the cancelable functions like write().
- They do not need to check parameters etc. */
+ They do not need to check parameters etc. This function must be
+ AS-safe, with the exception of the actual cancellation, because they
+ are called by wrappers around AS-safe functions like write().*/
int
attribute_hidden
__pthread_enable_asynccancel (void)
@@ -59,7 +61,9 @@ __pthread_enable_asynccancel (void)
return oldval;
}
-
+/* This function must be AS-safe, with the exception of the actual
+ cancellation, because they are called by wrappers around AS-safe
+ functions like write().*/
void
attribute_hidden
__pthread_disable_asynccancel (int oldtype)