[patch] fix tkill_failed gcc warning in gdbserver
Doug Evans
dje@google.com
Mon Dec 21 20:10:00 GMT 2009
Hi.
android doesn't have SYS_tkill but it does have __NR_tkill.
I will check this in tomorrow, pending objections.
This includes some minor tweaking to linux-nat.c:kill_lwp.
The code changes are technically better, and I like the consistency.
2009-12-21 Doug Evans <dje@google.com>
gdb/
* linux-nat.c (kill_lwp): Minor cleanup, move definition of
tkill_failed into ifdef HAVE_TKILL_SYSCALL. Move setting of errno
there too. Delete unnecessary resetting of errno after syscall.
Minor comment changes to match gdbserver/linux-low.c:kill_lwp.
gdbserver/
* configure.ac: Look for both __NR_tkill and SYS_tkill.
Define TKILL_SYSCALL_NAME to the one we find, if any.
* config.in: Regenerate.
* configure: Regenerate.
* linux-low.c (kill_lwp): Move definition of tkill_failed to
ifdef TKILL_SYSCALL_NAME to avoid gcc warning. Move setting of errno
there too. Delete unnecessary resetting of errno after syscall.
Minor comment changes to match gdb/linux-nat.c:kill_lwp.
Index: linux-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/linux-nat.c,v
retrieving revision 1.156
diff -u -p -r1.156 linux-nat.c
--- linux-nat.c 20 Nov 2009 19:48:45 -0000 1.156
+++ linux-nat.c 21 Dec 2009 19:43:51 -0000
@@ -2034,27 +2034,29 @@ linux_nat_resume (struct target_ops *ops
target_async (inferior_event_handler, 0);
}
-/* Issue kill to specified lwp. */
-
-static int tkill_failed;
+/* Send a signal to an LWP. */
static int
kill_lwp (int lwpid, int signo)
{
- errno = 0;
-
-/* Use tkill, if possible, in case we are using nptl threads. If tkill
- fails, then we are not using nptl threads and we should be using kill. */
+ /* Use tkill, if possible, in case we are using nptl threads. If tkill
+ fails, then we are not using nptl threads and we should be using kill. */
#ifdef HAVE_TKILL_SYSCALL
- if (!tkill_failed)
- {
- int ret = syscall (__NR_tkill, lwpid, signo);
- if (errno != ENOSYS)
- return ret;
- errno = 0;
- tkill_failed = 1;
- }
+ {
+ static int tkill_failed;
+
+ if (!tkill_failed)
+ {
+ int ret;
+
+ errno = 0;
+ ret = syscall (__NR_tkill, lwpid, signo);
+ if (errno != ENOSYS)
+ return ret;
+ tkill_failed = 1;
+ }
+ }
#endif
return kill (lwpid, signo);
Index: gdbserver/configure.ac
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/configure.ac,v
retrieving revision 1.30
diff -u -p -r1.30 configure.ac
--- gdbserver/configure.ac 17 Nov 2009 17:58:15 -0000 1.30
+++ gdbserver/configure.ac 21 Dec 2009 19:43:51 -0000
@@ -1,5 +1,5 @@
dnl Autoconf configure script for GDB server.
-dnl Copyright (C) 2000, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+dnl Copyright (C) 2000, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
dnl Free Software Foundation, Inc.
dnl
dnl This file is part of GDB.
@@ -196,6 +205,34 @@ AS_HELP_STRING([--with-libthread-db=PATH
srv_libs="$srv_libthread_db_path"
])
+dnl See if sys/syscall.h has __NR_tkill or SYS_tkill.
+AC_CACHE_CHECK([whether <sys/syscall.h> has __NR_tkill],
+ gdb_cv_sys_syscall_h_has_NR_tkill,
+ AC_TRY_COMPILE(
+ [#include <sys/syscall.h>],
+ [int i = __NR_tkill;],
+ gdb_cv_sys_syscall_h_has_NR_tkill=yes,
+ gdb_cv_sys_syscall_h_has_NR_tkill=no
+ )
+)
+if test "x$gdb_cv_sys_syscall_h_has_NR_tkill" != "xyes"; then
+ AC_CACHE_CHECK([whether <sys/syscall.h> has __SYS_tkill],
+ gdb_cv_sys_syscall_h_has_SYS_tkill,
+ AC_TRY_COMPILE(
+ [#include <sys/syscall.h>],
+ [int i = SYS_tkill;],
+ gdb_cv_sys_syscall_h_has_SYS_tkill=yes,
+ gdb_cv_sys_syscall_h_has_SYS_tkill=no
+ )
+ )
+fi
+dnl See if we can issue tkill syscall.
+if test "x$gdb_cv_sys_syscall_h_has_NR_tkill" = "xyes"; then
+ AC_DEFINE(TKILL_SYSCALL_NAME, __NR_tkill, [Name of the tkill syscall.])
+elif test "x$gdb_cv_sys_syscall_h_has_SYS_tkill" = "xyes"; then
+ AC_DEFINE(TKILL_SYSCALL_NAME, SYS_tkill, [Name of the tkill syscall.])
+fi
+
if test "$srv_xmlfiles" != ""; then
srv_xmlbuiltin="xml-builtin.o"
AC_DEFINE(USE_XML, 1, [Define if an XML target description is available.])
Index: gdbserver/linux-low.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/linux-low.c,v
retrieving revision 1.117
diff -u -p -r1.117 linux-low.c
--- gdbserver/linux-low.c 21 Dec 2009 17:54:03 -0000 1.117
+++ gdbserver/linux-low.c 21 Dec 2009 19:43:51 -0000
@@ -1572,25 +1572,29 @@ linux_wait (ptid_t ptid,
return event_ptid;
}
-/* Send a signal to an LWP. For LinuxThreads, kill is enough; however, if
- thread groups are in use, we need to use tkill. */
+/* Send a signal to an LWP. */
static int
kill_lwp (unsigned long lwpid, int signo)
{
- static int tkill_failed;
+ /* Use tkill, if possible, in case we are using nptl threads. If tkill
+ fails, then we are not using nptl threads and we should be using kill. */
- errno = 0;
-
-#ifdef SYS_tkill
- if (!tkill_failed)
- {
- int ret = syscall (SYS_tkill, lwpid, signo);
- if (errno != ENOSYS)
- return ret;
- errno = 0;
- tkill_failed = 1;
- }
+#ifdef TKILL_SYSCALL_NAME
+ {
+ static int tkill_failed;
+
+ if (!tkill_failed)
+ {
+ int ret;
+
+ errno = 0;
+ ret = syscall (TKILL_SYSCALL_NAME, lwpid, signo);
+ if (errno != ENOSYS)
+ return ret;
+ tkill_failed = 1;
+ }
+ }
#endif
return kill (lwpid, signo);
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