Changeset 872

Timestamp:

Nov 23, 2003, 3:41:33 AM (22 years ago)

Author:

bird

Message:

Added deadlock and termination checks to the semaphore waiting to avoid stupid hangs.

Location:

trunk/src/emx

Files:

• include/sys/fmutex.h (modified) (1 diff, 1 prop)
• src/lib/process/fmutex.c (modified) (3 diffs, 1 prop)

trunk/src/emx/include/sys/fmutex.h

@@ -34 +34 @@
 typedef struct
 {
-  unsigned long hev;            /* HEV */
-  __volatile__ signed char fs;  /* Status */
+    /** Handle to event semaphore. */
+    unsigned long hev;
+    /** Semaphore status. */
+    __volatile__ signed char fs;
+    /** Semaphore create flags. (_FMC_SHARED) */
+    unsigned char flags;
+    /** padding the struct to 8 bytes. */
+    unsigned char padding[2];
 } _fmutex;
 #pragma pack()

trunk/src/emx/src/lib/process/fmutex.c

@@ -20 +20 @@
   FS_VAR();
   sem->fs = _FMS_AVAILABLE;
+  sem->flags = flags;
+  sem->padding[0] = 'f';
+  sem->padding[1] = 'm';
   FS_SAVE_LOAD();
   rc = DosCreateEventSem (NULL, (PHEV)&sem->hev,
@@ -55 +58 @@
 {
   ULONG rc, count;
+  PTIB  pTib;
+  PPIB  pPib;
 
   if (fs == _FMS_UNINIT)
@@ -79 +84 @@
       if (__cxchg (&sem->fs, _FMS_OWNED_HARD) == _FMS_AVAILABLE)
         return 0;
+      FS_SAVE_LOAD();
+
       do
         {
-          FS_SAVE_LOAD();
-          rc = DosWaitEventSem (sem->hev, SEM_INDEFINITE_WAIT);
-          FS_RESTORE();
-        } while (rc == ERROR_INTERRUPT && (flags & _FMR_IGNINT));
+          rc = DosWaitEventSem (sem->hev, sem->flags & _FMC_SHARED ? SEM_INDEFINITE_WAIT : 3000);
+          if (rc == ERROR_INTERRUPT)
+            {
+              /*
+               * An interrupt occured, this might be a bug in the wait, or
+               * more likely someone is killing us. If we're dying/exiting or
+               * something along those lines, we return to the caller no matter
+               * what flags it specified.
+               */
+              if (!(flags & _FMR_IGNINT))
+                  break;
+              DosGetInfoBlocks(&pTib, &pPib);
+              if (pPib->pib_flstatus & (0x40/*dying*/ | 0x04/*exiting all*/ | 0x02/*Exiting Thread 1*/ | 0x01/* ExitList */))
+                  break;
+              rc = ERROR_TIMEOUT;
+            }
+          if (rc == ERROR_TIMEOUT && !(sem->flags & _FMC_SHARED))
+            {
+              /*
+               * Deadlock detection - if this is the only thread of the
+               * process we should just kill our selves.
+               * ASSUME thread ids are reused and upper thread limit or 4k.
+               */
+              int iThread;
+              DosGetInfoBlocks(&pTib, &pPib);
+              for (iThread = 1; iThread < 4096; iThread++)
+                {
+                  if (   iThread != pTib->tib_ptib2->tib2_ultid
+                      && !DosVerifyPidTid(pPib->pib_ulpid, iThread))
+                      break;
+                }
+              if (iThread >= 4096)
+                { /* No other threads! */
+                  ULONG ul;
+                  DosWrite((HFILE)2/*stderr*/, "\r\n!!!deadlock!!!\r\r", 18, &ul);
+                  __asm__ __volatile__ ("movl $0xdead10cc, %%eax; movl $0xdead10cc, %%edx; movl %0, %%ecx; int $3" : : "m" (sem) : "%eax", "%edx", "%ecx");
+                  rc = ERROR_SEM_OWNER_DIED;
+                  break;
+                }
+            }
+        } while (rc == ERROR_TIMEOUT);
+      FS_RESTORE();
       if (rc != 0)
         return rc;