Improve pthread signaling.

Remove xpool data type that required a lock on insertion / on seek and replace
it by an array of pids. On the array of pids, each thread place its pid in his
own reserved entry. Any one who wishes to signal a pthread peer, checks that
array for a valid pid.

diff --git a/xseg/drivers/kernel/xseg_pthread.c b/xseg/drivers/kernel/xseg_pthread.c
index 674b00d..395ecd8 100644 (file)
--- a/xseg/drivers/kernel/xseg_pthread.c
+++ b/xseg/drivers/kernel/xseg_pthread.c
@@ -86,10 +86,10 @@ static int pthread_wait_signal(struct xseg *xseg, uint32_t timeout)
 static int pthread_signal(struct xseg *xseg, uint32_t portno)
 {
        struct pid *pid;
+       int i;
+       pid_t cue = 0;
        struct task_struct *task;
        int ret = -ENOENT;
-       xpool_data data;
-       xpool_index idx;
        struct pthread_signal_desc *psd;
        struct xseg_port *port = xseg_get_port(xseg, portno);
        if (!port) 
@@ -100,14 +100,20 @@ static int pthread_signal(struct xseg *xseg, uint32_t portno)
 
        rcu_read_lock();
        /* XXX Security: xseg peers can kill anyone */
-       idx = xpool_peek(&psd->waiters, &data, portno); //FIXME portno is not the caller but the callee
-       if (idx == NoIndex){
-               /* no waiters */
+
+       for (i = 0; i < MAX_WAITERS; i++) {
+               cue = psd->pids[i];
+               if (cue)
+                       break;
+       }
+       if (!cue){
+               /* no waiters found */
                ret = 0;
                goto out;
        }
 
-       pid = find_vpid((pid_t) data);
+
+       pid = find_vpid(cue);
        if (!pid)
                goto out;
        task = pid_task(pid, PIDTYPE_PID);

diff --git a/xseg/drivers/user/xseg_pthread.c b/xseg/drivers/user/xseg_pthread.c
index d1ddc98..8c6ddd9 100644 (file)
--- a/xseg/drivers/user/xseg_pthread.c
+++ b/xseg/drivers/user/xseg_pthread.c
@@ -137,20 +137,22 @@ static void handler(int signum)
 
 static pthread_key_t pid_key, xpidx_key;
 static pthread_key_t mask_key, act_key;
+static pthread_key_t id_key;
 static pthread_once_t once_init = PTHREAD_ONCE_INIT;
 static pthread_once_t once_quit = PTHREAD_ONCE_INIT;
 static int isInit;
+static volatile int id = 0;
 
-static void keys_init(void) 
+static void keys_init(void)
 {
        int r;
-       
+
        r = pthread_key_create(&pid_key, NULL);
        if (r < 0) {
                isInit = 0;
                return;
        }
-       
+
        r = pthread_key_create(&xpidx_key, NULL);
        if (r < 0) {
                isInit = 0;
@@ -161,34 +163,39 @@ static void keys_init(void)
                isInit = 0;
                return;
        }
-       
+
        r = pthread_key_create(&act_key, NULL);
        if (r < 0) {
                isInit = 0;
                return;
        }
+       r = pthread_key_create(&id_key, NULL);
+       if (r < 0) {
+               isInit = 0;
+               return;
+       }
        isInit = 1;
        once_quit = PTHREAD_ONCE_INIT;
 }
 
 #define INT_TO_POINTER(__myptr, __myint) \
        do {\
-               unsigned long __foo__ = (unsigned long) __myint; \
-               __myptr = (void *) __foo__ ; \
+               unsigned long __foo____myptr = (unsigned long) __myint; \
+               __myptr = (void *) __foo____myptr ; \
        } while (0)
 
 #define POINTER_TO_INT(__myint, __myptr)\
        do { \
-               unsigned long __foo__ = (unsigned long) __myptr; \
-               __myint = (int) __foo__ ; \
+               unsigned long __foo____myint = (unsigned long) __myptr; \
+               __myint = (int) __foo____myint ; \
        } while (0)
 
 /* must be called by each thread */
 static int pthread_local_signal_init(struct xseg *xseg, xport portno)
 {
-       int r;
+       int r, my_id;
        pid_t pid;
-       void *tmp;
+       void *tmp, *tmp2;
        sigset_t *savedset, *set;
        struct sigaction *act, *old_act;
 
@@ -225,11 +232,17 @@ static int pthread_local_signal_init(struct xseg *xseg, xport portno)
                goto err6;
 
 
+       my_id = *(volatile int *) &id;
+       while (!__sync_bool_compare_and_swap(&id, my_id, my_id+1)){
+               my_id = *(volatile int *) &id;
+       }
        pid = syscall(SYS_gettid);
        INT_TO_POINTER(tmp, pid);
-       if (!pthread_setspecific(pid_key, tmp) ||
+       INT_TO_POINTER(tmp2, my_id);
+       if (pthread_setspecific(pid_key, tmp) ||
                        pthread_setspecific(mask_key, savedset) ||
-                       pthread_setspecific(act_key, old_act))
+                       pthread_setspecific(act_key, old_act) ||
+                       pthread_setspecific(id_key, tmp2))
                goto err7;
 
        return 0;
@@ -278,7 +291,7 @@ static int pthread_prepare_wait(struct xseg *xseg, uint32_t portno)
 {
        void * tmp;
        pid_t pid;
-       xpool_index r;
+       int my_id;
        struct xseg_port *port = xseg_get_port(xseg, portno);
        if (!port) 
                return -1;
@@ -290,38 +303,33 @@ static int pthread_prepare_wait(struct xseg *xseg, uint32_t portno)
        POINTER_TO_INT(pid, tmp);
        if (!pid)
                return -1;
-
-       r = xpool_add(&psd->waiters, (xpool_index) pid, portno); 
-       if (r == NoIndex)
-               return -1;
-       pthread_setspecific(xpidx_key, (void *)r);
+       tmp = pthread_getspecific(id_key);
+       POINTER_TO_INT(my_id, tmp);
+       psd->pids[my_id] = pid;
        return 0;
 }
 
 static int pthread_cancel_wait(struct xseg *xseg, uint32_t portno)
 {
        void * tmp;
+       int my_id;
        pid_t pid;
-       xpool_data data;
-       xpool_index xpidx, r;
        struct xseg_port *port = xseg_get_port(xseg, portno);
-       if (!port) 
+       if (!port)
                return -1;
        struct pthread_signal_desc *psd = xseg_get_signal_desc(xseg, port);
        if (!psd)
                return -1;
-       
+
        tmp = pthread_getspecific(pid_key);
        POINTER_TO_INT(pid, tmp);
        if (!pid)
                return -1;
 
-       xpidx = (xpool_index) pthread_getspecific(xpidx_key);
+       tmp = pthread_getspecific(id_key);
+       POINTER_TO_INT(my_id, tmp);
+       psd->pids[my_id] = 0;
 
-       r = xpool_remove(&psd->waiters, xpidx, &data, portno);
-       if (r == NoIndex)
-               return -1;
-       
        return 0;
 }
 
@@ -346,8 +354,7 @@ static int pthread_wait_signal(struct xseg *xseg, uint32_t usec_timeout)
 
 static int pthread_signal(struct xseg *xseg, uint32_t portno)
 {
-       xpool_data data;
-       xpool_index idx;
+       int i;
 
        struct xseg_port *port = xseg_get_port(xseg, portno);
        if (!port) 
@@ -356,15 +363,15 @@ static int pthread_signal(struct xseg *xseg, uint32_t portno)
        if (!psd)
                return -1;
 
-       idx = xpool_peek(&psd->waiters, &data, portno); //FIXME portno is not the caller but the callee
-       if (idx == NoIndex) 
-               return 0;
-
-       pid_t cue = (pid_t) data;
-       if (!cue)
-               return 0;
+       pid_t cue;
+       for (i = 0; i < MAX_WAITERS; i++) {
+               cue = psd->pids[i];
+               if (cue)
+                       return syscall(SYS_tkill, cue, SIGIO);
+       }
 
-       return syscall(SYS_tkill, cue, SIGIO);
+       /* no waiter found */
+       return 0;
 }
 
 static void *pthread_malloc(uint64_t size)
@@ -397,16 +404,21 @@ static struct xseg_type xseg_pthread = {
 
 int pthread_init_signal_desc(struct xseg *xseg, void *sd)
 {
+       int i;
        struct pthread_signal_desc *psd = (struct pthread_signal_desc *)sd;
-       xpool_init(&psd->waiters, MAX_WAITERS, psd->bufs);
-       xpool_clear(&psd->waiters, 1);
+       for (i = 0; i < MAX_WAITERS; i++) {
+               psd->pids[i]=0;
+       }
        return 0;
 }
 
 void pthread_quit_signal_desc(struct xseg *xseg, void *sd)
 {
+       int i;
        struct pthread_signal_desc *psd = (struct pthread_signal_desc *)sd;
-       xpool_clear(&psd->waiters, 1);
+       for (i = 0; i < MAX_WAITERS; i++) {
+               psd->pids[i]=0;
+       }
        return;
 }
 

diff --git a/xseg/drivers/xseg_pthread.h b/xseg/drivers/xseg_pthread.h
index cebc106..07f2b26 100644 (file)
--- a/xseg/drivers/xseg_pthread.h
+++ b/xseg/drivers/xseg_pthread.h
@@ -38,6 +38,5 @@
 #define MAGIC_PTHREAD_SD 7
 
 struct pthread_signal_desc{
-       struct xpool waiters;
-       struct xpool_node bufs[MAX_WAITERS];
-};  
+       volatile pid_t pids[MAX_WAITERS];
+};