[PATCH] D29954: [PGO] Suspend SIGKILL for PR_SET_PDEATHSIG in profile-write

[Rong Xu via Phabricator via llvm-commits]

xur updated this revision to Diff 88418.
xur added a comment.

move platform depended code to InstrProfilingUnil.c per David's suggestion.


https://reviews.llvm.org/D29954

Files:
  lib/profile/InstrProfilingFile.c
  lib/profile/InstrProfilingUtil.c
  lib/profile/InstrProfilingUtil.h


Index: lib/profile/InstrProfilingUtil.h
===================================================================
--- lib/profile/InstrProfilingUtil.h
+++ lib/profile/InstrProfilingUtil.h
@@ -51,4 +51,12 @@
 unsigned lprofBoolCmpXchg(void **Ptr, void *OldV, void *NewV);
 void *lprofPtrFetchAdd(void **Mem, long ByteIncr);
 
+/* Temporarily suspend SIGKILL. Return value of 1 means a restore is needed.
+ * Other return values mean no restore is needed.
+ */
+int lprofSuspendSigKill();
+
+/* Restore previously suspended SIGKILL. */
+void lprofRestoreSigKill();
+
 #endif /* PROFILE_INSTRPROFILINGUTIL_H */
Index: lib/profile/InstrProfilingUtil.c
===================================================================
--- lib/profile/InstrProfilingUtil.c
+++ lib/profile/InstrProfilingUtil.c
@@ -29,6 +29,11 @@
 #include <stdlib.h>
 #include <string.h>
 
+#if defined(__linux__)
+#include <signal.h>
+#include <sys/prctl.h>
+#endif
+
 COMPILER_RT_VISIBILITY
 void __llvm_profile_recursive_mkdir(char *path) {
   int i;
@@ -219,3 +224,21 @@
 #endif
   return Sep;
 }
+
+COMPILER_RT_VISIBILITY int lprofSuspendSigKill() {
+#if defined(__linux__)
+  int PDeachSig = 0;
+  /* Temporarily suspend getting SIGKILL upon exit of the parent process. */
+  if (prctl(PR_GET_PDEATHSIG, &PDeachSig) == 0 && PDeachSig == SIGKILL)
+    prctl(PR_SET_PDEATHSIG, 0);
+  return (PDeachSig == SIGKILL);
+#else
+  return 0;
+#endif
+}
+
+COMPILER_RT_VISIBILITY void lprofRestoreSigKill() {
+#if defined(__linux__)
+  prctl(PR_SET_PDEATHSIG, SIGKILL);
+#endif
+}
Index: lib/profile/InstrProfilingFile.c
===================================================================
--- lib/profile/InstrProfilingFile.c
+++ lib/profile/InstrProfilingFile.c
@@ -524,6 +524,7 @@
   int rc, Length;
   const char *Filename;
   char *FilenameBuf;
+  int PDeathSig = 0;
 
   if (lprofProfileDumped()) {
     PROF_NOTE("Profile data not written to file: %s.\n", 
@@ -550,10 +551,18 @@
     return -1;
   }
 
+  // Temporarily suspend getting SIGKILL when the parent exits.
+  PDeathSig = lprofSuspendSigKill();
+
   /* Write profile data to the file. */
   rc = writeFile(Filename);
   if (rc)
     PROF_ERR("Failed to write file \"%s\": %s\n", Filename, strerror(errno));
+
+  // Restore SIGKILL.
+  if (PDeathSig == 1)
+    lprofRestoreSigKill();
+
   return rc;
 }
 


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