[PATCH v2 15/19] nptl: Use tidlock when accessing TID on pthread_getname_np
Adhemerval Zanella
adhemerval.zanella@linaro.org
Mon Aug 23 19:50:43 GMT 2021
Checked on x86_64-linux-gnu.
---
nptl/pthread_getname.c | 45 ++++++++++++++++++++++++++----------------
1 file changed, 28 insertions(+), 17 deletions(-)
diff --git a/nptl/pthread_getname.c b/nptl/pthread_getname.c
index 8ac814366a..37dd6a360e 100644
--- a/nptl/pthread_getname.c
+++ b/nptl/pthread_getname.c
@@ -22,6 +22,7 @@
#include <stdio.h>
#include <string.h>
#include <unistd.h>
+#include <intprops.h>
#include <sys/prctl.h>
#include <not-cancel.h>
#include <shlib-compat.h>
@@ -29,7 +30,7 @@
int
__pthread_getname_np (pthread_t th, char *buf, size_t len)
{
- const struct pthread *pd = (const struct pthread *) th;
+ struct pthread *pd = (struct pthread *) th;
/* Unfortunately the kernel headers do not export the TASK_COMM_LEN
macro. So we have to define it here. */
@@ -40,29 +41,39 @@ __pthread_getname_np (pthread_t th, char *buf, size_t len)
if (pd == THREAD_SELF)
return __prctl (PR_GET_NAME, buf) ? errno : 0;
-#define FMT "/proc/self/task/%u/comm"
- char fname[sizeof (FMT) + 8];
- sprintf (fname, FMT, (unsigned int) pd->tid);
+ /* Block all signal, since the lock is recursive and used on pthread_cancel
+ (which should be async-signal-safe). */
+ sigset_t oldmask;
+ __libc_signal_block_all (&oldmask);
+ lll_lock (pd->tidlock, LLL_PRIVATE);
- int fd = __open64_nocancel (fname, O_RDONLY);
- if (fd == -1)
- return errno;
+ char fname[sizeof ("/proc/self/task//comm" ) + INT_BUFSIZE_BOUND (pid_t)];
+ __snprintf (fname, sizeof (fname), "/proc/self/task/%d/comm", pd->tid);
int res = 0;
- ssize_t n = TEMP_FAILURE_RETRY (__read_nocancel (fd, buf, len));
- if (n < 0)
- res = errno;
- else
+ int fd = __open64_nocancel (fname, O_RDONLY);
+ if (fd != -1)
{
- if (buf[n - 1] == '\n')
- buf[n - 1] = '\0';
- else if (n == len)
- res = ERANGE;
+ ssize_t n = TEMP_FAILURE_RETRY (__read_nocancel (fd, buf, len));
+ if (n > 0)
+ {
+ if (buf[n - 1] == '\n')
+ buf[n - 1] = '\0';
+ else if (n == len)
+ res = ERANGE;
+ else
+ buf[n] = '\0';
+ }
else
- buf[n] = '\0';
+ res = errno;
+
+ __close_nocancel_nostatus (fd);
}
+ else
+ res = errno;
- __close_nocancel_nostatus (fd);
+ lll_unlock (pd->tidlock, LLL_PRIVATE);
+ __libc_signal_restore_set (&oldmask);
return res;
}
--
2.30.2
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