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authorMark Kettenis <kettenis@gnu.org>2000-09-09 07:54:20 +0000
committerMark Kettenis <kettenis@gnu.org>2000-09-09 07:54:20 +0000
commit3f07c44bc9f1a80bdf5b44f363a6d85a7e07f8aa (patch)
tree19d5cca0e4ad3762294c4881ed57e36b05031117 /gdb/lin-lwp.c
parent7318608963cb576278b3cd025aa60ee2671e2861 (diff)
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* lin-lwp.c (normal_mask, blocked_mask): New variables.
(lin_lwp_wait): Block SIGCHLD here if it isn't already blocked. (lin_lwp_mourn_inferior): Restore the origional signal mask, and reset the mask of blocked signals. (_initialize_lin_lwp): Don't block SIGCHLD here, but do initialize suspend_mask and blocked_mask. This makes us pass gdb.base/sigall.exp for Linux/x86 now. (lin_thread_get_thread_signals): Treat the LinuxThreads "cancel" signal similarly to SIGCHLD in the generic code. Avoids GDB being terminated by a Real-time signal.
Diffstat (limited to 'gdb/lin-lwp.c')
-rw-r--r--gdb/lin-lwp.c76
1 files changed, 62 insertions, 14 deletions
diff --git a/gdb/lin-lwp.c b/gdb/lin-lwp.c
index 3b0812e..59de118 100644
--- a/gdb/lin-lwp.c
+++ b/gdb/lin-lwp.c
@@ -55,9 +55,11 @@ extern const char *strsignal (int sig);
code:
- In general one should specify the __WCLONE flag to waitpid in
- order to make it report events for any of the cloned processes.
- However, if a cloned process has exited the exit status is only
- reported if the __WCLONE flag is absent.
+ order to make it report events for any of the cloned processes
+ (and leave it out for the initial process). However, if a cloned
+ process has exited the exit status is only reported if the
+ __WCLONE flag is absent. Linux 2.4 has a __WALL flag, but we
+ cannot use it since GDB must work on older systems too.
- When a traced, cloned process exits and is waited for by the
debugger, the kernel reassigns it to the origional parent and
@@ -126,9 +128,26 @@ static struct target_ops lin_lwp_ops;
/* The standard child operations. */
extern struct target_ops child_ops;
+/* Since we cannot wait (in lin_lwp_wait) for the initial process and
+ any cloned processes with a single call to waitpid, we have to use
+ use the WNOHANG flag and call waitpid in a loop. To optimize
+ things a bit we use `sigsuspend' to wake us up when a process has
+ something to report (it will send us a SIGCHLD if it has). To make
+ this work we have to juggle with the signal mask. We save the
+ origional signal mask such that we can restore it before creating a
+ new process in order to avoid blocking certain signals in the
+ inferior. We then block SIGCHLD during the waitpid/sigsuspend
+ loop. */
+
+/* Origional signal mask. */
+static sigset_t normal_mask;
+
/* Signal mask for use with sigsuspend in lin_lwp_wait, initialized in
_initialize_lin_lwp. */
static sigset_t suspend_mask;
+
+/* Signals to block to make that sigsuspend work. */
+static sigset_t blocked_mask;
/* Prototypes for local functions. */
@@ -479,7 +498,7 @@ stop_wait_callback (struct lwp_info *lp, void *data)
is_cloned (lp->pid) ? __WCLONE : 0);
if (pid == -1 && errno == ECHILD)
/* OK, the proccess has disappeared. We'll catch the actual
- exit event in lin_lwp_wait. */
+ exit event in lin_lwp_wait. */
return 0;
gdb_assert (pid == GET_LWP (lp->pid));
@@ -575,6 +594,13 @@ lin_lwp_wait (int pid, struct target_waitstatus *ourstatus)
int options = 0;
int status = 0;
+ /* Make sure SIGCHLD is blocked. */
+ if (! sigismember (&blocked_mask, SIGCHLD))
+ {
+ sigaddset (&blocked_mask, SIGCHLD);
+ sigprocmask (SIG_BLOCK, &blocked_mask, NULL);
+ }
+
retry:
/* First check if there is a LWP with a wait status pending. */
@@ -659,7 +685,8 @@ lin_lwp_wait (int pid, struct target_waitstatus *ourstatus)
lp = add_lwp (BUILD_LWP (lwpid, inferior_pid));
if (threaded)
{
- gdb_assert (WIFSTOPPED (status) && WSTOPSIG (status) == SIGSTOP);
+ gdb_assert (WIFSTOPPED (status)
+ && WSTOPSIG (status) == SIGSTOP);
lp->signalled = 1;
if (! in_thread_list (inferior_pid))
@@ -863,6 +890,10 @@ lin_lwp_mourn_inferior (void)
trap_pid = 0;
+ /* Restore the origional signal mask. */
+ sigprocmask (SIG_SETMASK, &normal_mask, NULL);
+ sigemptyset (&blocked_mask);
+
#if 0
target_beneath = find_target_beneath (&lin_lwp_ops);
#else
@@ -978,7 +1009,6 @@ void
_initialize_lin_lwp (void)
{
struct sigaction action;
- sigset_t mask;
extern void thread_db_init (struct target_ops *);
@@ -986,18 +1016,19 @@ _initialize_lin_lwp (void)
add_target (&lin_lwp_ops);
thread_db_init (&lin_lwp_ops);
+ /* Save the origional signal mask. */
+ sigprocmask (SIG_SETMASK, NULL, &normal_mask);
+
action.sa_handler = sigchld_handler;
sigemptyset (&action.sa_mask);
action.sa_flags = 0;
sigaction (SIGCHLD, &action, NULL);
- /* We block SIGCHLD throughout this code ... */
- sigemptyset (&mask);
- sigaddset (&mask, SIGCHLD);
- sigprocmask (SIG_BLOCK, &mask, &suspend_mask);
-
- /* ... except during a sigsuspend. */
+ /* Make sure we don't block SIGCHLD during a sigsuspend. */
+ sigprocmask (SIG_SETMASK, NULL, &suspend_mask);
sigdelset (&suspend_mask, SIGCHLD);
+
+ sigemptyset (&blocked_mask);
}
@@ -1030,8 +1061,8 @@ get_signo (const char *name)
void
lin_thread_get_thread_signals (sigset_t *set)
{
- int restart;
- int cancel;
+ struct sigaction action;
+ int restart, cancel;
sigemptyset (set);
@@ -1045,4 +1076,21 @@ lin_thread_get_thread_signals (sigset_t *set)
sigaddset (set, restart);
sigaddset (set, cancel);
+
+ /* The LinuxThreads library makes terminating threads send a special
+ "cancel" signal instead of SIGCHLD. Make sure we catch those (to
+ prevent them from terminating GDB itself, which is likely to be
+ their default action) and treat them the same way as SIGCHLD. */
+
+ action.sa_handler = sigchld_handler;
+ sigemptyset (&action.sa_mask);
+ action.sa_flags = 0;
+ sigaction (cancel, &action, NULL);
+
+ /* We block the "cancel" signal throughout this code ... */
+ sigaddset (&blocked_mask, cancel);
+ sigprocmask (SIG_BLOCK, &blocked_mask, NULL);
+
+ /* ... except during a sigsuspend. */
+ sigdelset (&suspend_mask, cancel);
}