commit 853a1ce66afb2e5517bbac1dededea19a27b1534
author philippe <philippe@a5019735-40e9-0310-863c-91ae7b9d1cf9> Mon May 12 20:29:17 2014 +0000
committer philippe <philippe@a5019735-40e9-0310-863c-91ae7b9d1cf9> Mon May 12 20:29:17 2014 +0000
tree 3dab3be2f5c7605a3e7eb4e3bf3f8fba26910001
parent bd830b45bf40e077fb5c0ea6333a416971c253cd

In case gdbsrv poll syscall fails, produces more information
gdbsrv poll syscall seems to very infrequently (1 on 100000 vgdb invocations§)
to be EINTR-upted.
So, when poll syscall fails, output stacktrace + sigmask status
to capture more info about the problem.
This is a follow-up/extension of r13748, which showed poll was interrupted
but it is not clear why. In particular, all async signals are supposed
to be masked at the time vgdb has forced an invocation



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13953 a5019735-40e9-0310-863c-91ae7b9d1cf9

coregrind/m_gdbserver/remote-utils.c

diff --git a/coregrind/m_gdbserver/remote-utils.c b/coregrind/m_gdbserver/remote-utils.c
index 2bcb77f..d8dbe2a 100644
--- a/coregrind/m_gdbserver/remote-utils.c
+++ b/coregrind/m_gdbserver/remote-utils.c
@@ -33,6 +33,31 @@
 #include <sys/prctl.h>
 #  endif
 
+/* Calls sr_perror with msg.
+   Outputs more information about Valgrind state if verbosity > 0
+   or debuglog_getlevel > 0. */
+static
+void sr_extended_perror (SysRes sr, const HChar *msg)
+{
+   sr_perror (sr, msg);
+   if (VG_(clo_verbosity) > 0 || VG_(debugLog_getLevel)() >= 1) {
+      Int i;
+      vki_sigset_t cursigset;
+      VG_(show_sched_status) (True,  // host_stacktrace
+                              True,  // valgrind_stack_usage
+                              True); // exited_threads
+      VG_(sigprocmask) (0,           // dummy how.
+                        NULL,        // do not change the sigmask
+                        &cursigset); //
+      VG_(dmsg)("current sigmask value { ");
+      for (i = 1; i <= _VKI_NSIG; i++) {
+         if (VG_(sigismember)(&cursigset, i))
+            VG_(dmsg)("%u ", i);
+      }
+      VG_(dmsg)("}\n");
+   }
+}
+
 Bool noack_mode;
 
 static int readchar (int single);
@@ -171,7 +196,7 @@
       if (sr_isError(ret) 
           || (sr_Res(ret) > 0 && poll_cond(write_remote_desc_ok.revents))) {
         if (sr_isError(ret)) {
-          sr_perror(ret, "ensure_write_remote_desc: poll error\n");
+          sr_extended_perror(ret, "ensure_write_remote_desc: poll error\n");
         } else {
           dlog(0, "POLLcond %d closing write_remote_desc %d\n", 
                write_remote_desc_ok.revents, write_remote_desc);
@@ -366,7 +391,10 @@
    time to let a proper cleanup to be donex */
 void sync_gdb_connection(void)
 {
-   VG_(poll)(0, 0, 100);
+   SysRes ret;
+   ret = VG_(poll)(0, 0, 100);
+   if (sr_isError(ret))
+      sr_extended_perror(ret, "sync_gdb_connection: poll error\n");
 }
 
 static
@@ -470,7 +498,7 @@
    if (sr_isError(ret)
        || (sr_Res(ret) && poll_cond(remote_desc_pollfdread_activity.revents))) {
      if (sr_isError(ret)) {
-       sr_perror(ret, "remote_desc_activity: poll error\n");
+       sr_extended_perror(ret, "remote_desc_activity: poll error\n");
      } else {
        dlog(0, "POLLcond %d remote_desc_pollfdread %d\n", 
             remote_desc_pollfdread_activity.revents, remote_desc);
@@ -841,7 +869,7 @@
    ret = VG_(poll)(&remote_desc_pollfdread_activity, 1, -1);
    if (sr_isError(ret) || sr_Res(ret) != 1) {
      if (sr_isError(ret)) {
-        sr_perror(ret, "readchar: poll error\n");
+        sr_extended_perror(ret, "readchar: poll error\n");
      } else {
         dlog(0, "readchar: poll got %d, expecting 1\n", (int)sr_Res(ret));
      }