[Qemu-devel] [PULL 20/44] linux-user: Use safe_syscall for kill, tkill and tgkill syscalls

[riku.voipio@linaro.org]

From: Peter Maydell <peter.maydell@linaro.org>

Use the safe_syscall wrapper for the kill, tkill and tgkill syscalls.
Without this, if a thread sent a SIGKILL to itself it could kill the
thread before we had a chance to process a signal that arrived just
before the SIGKILL, and that signal would get lost.

We drop all the ifdeffery for tkill and tgkill, because every guest
architecture we support implements them, and they've been in Linux
since 2003 so we can assume the host headers define the __NR_tkill
and __NR_tgkill constants.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
---
 linux-user/syscall.c | 23 +++++++----------------
 1 file changed, 7 insertions(+), 16 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index f3061a9..c0d086c 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -191,8 +191,6 @@ static type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5,	\
 #define __NR_sys_getpriority __NR_getpriority
 #define __NR_sys_rt_sigqueueinfo __NR_rt_sigqueueinfo
 #define __NR_sys_syslog __NR_syslog
-#define __NR_sys_tgkill __NR_tgkill
-#define __NR_sys_tkill __NR_tkill
 #define __NR_sys_futex __NR_futex
 #define __NR_sys_inotify_init __NR_inotify_init
 #define __NR_sys_inotify_add_watch __NR_inotify_add_watch
@@ -230,12 +228,6 @@ _syscall5(int, _llseek,  uint,  fd, ulong, hi, ulong, lo,
 #endif
 _syscall3(int,sys_rt_sigqueueinfo,int,pid,int,sig,siginfo_t *,uinfo)
 _syscall3(int,sys_syslog,int,type,char*,bufp,int,len)
-#if defined(TARGET_NR_tgkill) && defined(__NR_tgkill)
-_syscall3(int,sys_tgkill,int,tgid,int,pid,int,sig)
-#endif
-#if defined(TARGET_NR_tkill) && defined(__NR_tkill)
-_syscall2(int,sys_tkill,int,tid,int,sig)
-#endif
 #ifdef __NR_exit_group
 _syscall1(int,exit_group,int,error_code)
 #endif
@@ -717,6 +709,9 @@ safe_syscall6(int, pselect6, int, nfds, fd_set *, readfds, fd_set *, writefds, \
 safe_syscall6(int,futex,int *,uaddr,int,op,int,val, \
               const struct timespec *,timeout,int *,uaddr2,int,val3)
 safe_syscall2(int, rt_sigsuspend, sigset_t *, newset, size_t, sigsetsize)
+safe_syscall2(int, kill, pid_t, pid, int, sig)
+safe_syscall2(int, tkill, int, tid, int, sig)
+safe_syscall3(int, tgkill, int, tgid, int, pid, int, sig)
 
 static inline int host_to_target_sock_type(int host_type)
 {
@@ -7169,7 +7164,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
         ret = 0;
         break;
     case TARGET_NR_kill:
-        ret = get_errno(kill(arg1, target_to_host_signal(arg2)));
+        ret = get_errno(safe_kill(arg1, target_to_host_signal(arg2)));
         break;
 #ifdef TARGET_NR_rename
     case TARGET_NR_rename:
@@ -10405,18 +10400,14 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
         break;
 #endif
 
-#if defined(TARGET_NR_tkill) && defined(__NR_tkill)
     case TARGET_NR_tkill:
-        ret = get_errno(sys_tkill((int)arg1, target_to_host_signal(arg2)));
+        ret = get_errno(safe_tkill((int)arg1, target_to_host_signal(arg2)));
         break;
-#endif
 
-#if defined(TARGET_NR_tgkill) && defined(__NR_tgkill)
     case TARGET_NR_tgkill:
-	ret = get_errno(sys_tgkill((int)arg1, (int)arg2,
+        ret = get_errno(safe_tgkill((int)arg1, (int)arg2,
                         target_to_host_signal(arg3)));
-	break;
-#endif
+        break;
 
 #ifdef TARGET_NR_set_robust_list
     case TARGET_NR_set_robust_list:
-- 
2.1.4