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* [glibc] nptl: Use pthread_kill on pthread_cancel
@ 2021-06-09 18:17 Adhemerval Zanella
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From: Adhemerval Zanella @ 2021-06-09 18:17 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a6c813d0ad0fd9830f2cd3c3d079af8d2aa50a1f
commit a6c813d0ad0fd9830f2cd3c3d079af8d2aa50a1f
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Mon Dec 7 17:17:24 2020 -0300
nptl: Use pthread_kill on pthread_cancel
It consolidates the tgkill call and it is the first step of making
pthread_cancel async-signal-safe. It also fix a possible issue
where the 'struct pthread' tid is not read atomically, which might
send an invalid cancellation signal (similar to what
db988e50a87f613cb6b9e98a2fc66a4848bc3546 fixed for pthread_join).
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Diff:
---
nptl/pthreadP.h | 2 ++
nptl/pthread_cancel.c | 6 +-----
nptl/pthread_kill.c | 18 ++++++++++++------
3 files changed, 15 insertions(+), 11 deletions(-)
diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
index 618922f47a..675d1de753 100644
--- a/nptl/pthreadP.h
+++ b/nptl/pthreadP.h
@@ -515,6 +515,8 @@ libc_hidden_proto (__pthread_detach)
extern int __pthread_kill (pthread_t threadid, int signo);
libc_hidden_proto (__pthread_kill)
extern int __pthread_cancel (pthread_t th);
+extern int __pthread_kill_internal (pthread_t threadid, int signo)
+ attribute_hidden;
extern void __pthread_exit (void *value) __attribute__ ((__noreturn__));
libc_hidden_proto (__pthread_exit)
extern int __pthread_join (pthread_t threadid, void **thread_return);
diff --git a/nptl/pthread_cancel.c b/nptl/pthread_cancel.c
index de4659a1f0..0698cd2046 100644
--- a/nptl/pthread_cancel.c
+++ b/nptl/pthread_cancel.c
@@ -110,11 +110,7 @@ __pthread_cancel (pthread_t th)
return 0;
}
- pid_t pid = __getpid ();
- int val = INTERNAL_SYSCALL_CALL (tgkill, pid, pd->tid, SIGCANCEL);
- return INTERNAL_SYSCALL_ERROR_P (val)
- ? INTERNAL_SYSCALL_ERRNO (val)
- : 0;
+ return __pthread_kill_internal (th, SIGCANCEL);
}
versioned_symbol (libc, __pthread_cancel, pthread_cancel, GLIBC_2_34);
diff --git a/nptl/pthread_kill.c b/nptl/pthread_kill.c
index 8982011ba8..f79a2b26fc 100644
--- a/nptl/pthread_kill.c
+++ b/nptl/pthread_kill.c
@@ -21,13 +21,8 @@
#include <shlib-compat.h>
int
-__pthread_kill (pthread_t threadid, int signo)
+__pthread_kill_internal (pthread_t threadid, int signo)
{
- /* Disallow sending the signal we use for cancellation, timers,
- for the setxid implementation. */
- if (__is_internal_signal (signo))
- return EINVAL;
-
pid_t tid;
struct pthread *pd = (struct pthread *) threadid;
@@ -55,6 +50,17 @@ __pthread_kill (pthread_t threadid, int signo)
return val;
}
+
+int
+__pthread_kill (pthread_t threadid, int signo)
+{
+ /* Disallow sending the signal we use for cancellation, timers,
+ for the setxid implementation. */
+ if (__is_internal_signal (signo))
+ return EINVAL;
+
+ return __pthread_kill_internal (threadid, signo);
+}
/* Some architectures (for instance arm) might pull raise through libgcc, so
avoid the symbol version if it ends up being used on ld.so. */
#if !IS_IN(rtld)
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