vserver 1.9.3

[linux-2.6.git] / arch / um / kernel / signal_user.c

diff --git a/arch/um/kernel/signal_user.c b/arch/um/kernel/signal_user.c
index 52cfd60..74a69e4 100644 (file)
--- a/arch/um/kernel/signal_user.c
+++ b/arch/um/kernel/signal_user.c
@@ -80,6 +80,12 @@ void unblock_signals(void)
        change_signals(SIG_UNBLOCK);
 }
 
+/* These are the asynchronous signals.  SIGVTALRM and SIGARLM are handled
+ * together under SIGVTALRM_BIT.  SIGPROF is excluded because we want to
+ * be able to profile all of UML, not just the non-critical sections.  If
+ * profiling is not thread-safe, then that is not my problem.  We can disable
+ * profiling when SMP is enabled in that case.
+ */
 #define SIGIO_BIT 0
 #define SIGVTALRM_BIT 1
 
@@ -114,6 +120,11 @@ int set_signals(int enable)
                sigaddset(&mask, SIGVTALRM);
                sigaddset(&mask, SIGALRM);
        }
+
+       /* This is safe - sigprocmask is guaranteed to copy locally the
+        * value of new_set, do his work and then, at the end, write to
+        * old_set.
+        */
        if(sigprocmask(SIG_UNBLOCK, &mask, &mask) < 0)
                panic("Failed to enable signals");
        ret = enable_mask(&mask);