[PATCH] longjmp implementation

[Darren Vincent Hart]

---
 mutexint.c |   27 +++++++++++++++++++--------
 1 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/mutexint.c b/mutexint.c
index 003717f..82a608b 100644
--- a/mutexint.c
+++ b/mutexint.c
@@ -37,6 +37,7 @@
 #include <sys/types.h>
 #include <linux/futex.h>
 #include <errno.h>
+#include <setjmp.h>
 
 /*
  * The futex() call has been removed from the include/futex.h header, implement
@@ -44,7 +45,8 @@
  */
 //#define SYS_futex 202
 #define FUTEX_PRIVATE 128
-#define FUTEX_INTERRUPTIBLE 512
+//#define FUTEX_INTERRUPTIBLE 512
+#define FUTEX_INTERRUPTIBLE 0
 #define futex(uaddr, op, val, timeout, uaddr2, val3) \
 	syscall(SYS_futex, uaddr, op, val, timeout, uaddr2, val3)
 
@@ -59,6 +61,9 @@
 
 #define SIGMUTEXINT SIGRTMIN
 
+/* Need some kind of per-thread variable here */
+jmp_buf env;
+
 /*
  * Implement cmpxchg using gcc atomic builtins.
  * http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
@@ -80,6 +85,7 @@ struct mutexint_attr {
 void sigmutexint_handler(int signo)
 {
 	printf("handled cancel signal: %d\n", signo);
+	longjmp(env, 1);
 }
 
 int mutexint_init(struct mutexint *mutex, struct mutexint_attr *attr)
@@ -102,13 +108,18 @@ int mutexint_lock(struct mutexint *mutex)
 			if ((val & FUTEX_WAITERS) || 
 				(val = cmpxchg(&mutex->lock_val, val, val | FUTEX_WAITERS))) {
 				printf("\tinner cmpxchg old_val: 0x%x lock_val: 0x%x\n", val, mutex->lock_val);
-				printf("\tcalling futex_lock_pi:\n");
-				printf("\top: 0x%x\n", FUTEX_LOCK_PI | FUTEX_PRIVATE | FUTEX_INTERRUPTIBLE);
-				printf("\t&lock_val: %p\n", &mutex->lock_val);
-				ret = futex_lock_pi(&mutex->lock_val, val, NULL);
-				if (ret == -1) {
-					ret = -errno;
-					printf("futex_lock_pi returned -1, errno is %d\n", ret);
+				if (setjmp(env)) {
+					printf("mutexint_lock canceled, aborting\n");
+					ret = -EINTR;
+				} else {
+					printf("\tcalling futex_lock_pi:\n");
+					printf("\top: 0x%x\n", FUTEX_LOCK_PI | FUTEX_PRIVATE | FUTEX_INTERRUPTIBLE);
+					printf("\t&lock_val: %p\n", &mutex->lock_val);
+					ret = futex_lock_pi(&mutex->lock_val, val, NULL);
+					if (ret == -1) {
+						ret = -errno;
+						printf("futex_lock_pi returned -1, errno is %d\n", ret);
+					}
 				}
 				/*
 				 * If -EINTR is returned, the lock may no longer
-- 
1.6.0.4


-- 
Darren Hart
IBM Linux Technology Center
Real-Time Linux Team
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