avoid all malloc/free in timer creation/destruction

instead of allocating a userspace structure for signal-based timers,
simply use the kernel timer id. we use the fact that thread pointers
will always be zero in the low bit (actually more) to encode integer
timerid values as pointers.

also, this change ensures that the timer_destroy syscall has completed
before the library timer_destroy function returns, in case it matters.

diff --git a/arch/i386/bits/alltypes.h.sh b/arch/i386/bits/alltypes.h.sh
index 13658cc..c6201b9 100755 (executable)
--- a/arch/i386/bits/alltypes.h.sh
+++ b/arch/i386/bits/alltypes.h.sh
@@ -107,7 +107,7 @@ TYPEDEF long long blkcnt_t;
 TYPEDEF unsigned long long fsblkcnt_t;
 TYPEDEF unsigned long long fsfilcnt_t;
 
-TYPEDEF struct __timer * timer_t;
+TYPEDEF void * timer_t;
 TYPEDEF int clockid_t;
 TYPEDEF unsigned long clock_t;
 

diff --git a/arch/x86_64/bits/alltypes.h.sh b/arch/x86_64/bits/alltypes.h.sh
index cd84a2d..b0aecd9 100755 (executable)
--- a/arch/x86_64/bits/alltypes.h.sh
+++ b/arch/x86_64/bits/alltypes.h.sh
@@ -107,7 +107,7 @@ TYPEDEF long long blkcnt_t;
 TYPEDEF unsigned long long fsblkcnt_t;
 TYPEDEF unsigned long long fsfilcnt_t;
 
-TYPEDEF struct __timer * timer_t;
+TYPEDEF void * timer_t;
 TYPEDEF int clockid_t;
 TYPEDEF long clock_t;
 

diff --git a/src/time/timer_create.c b/src/time/timer_create.c
index 89099dd..c5894f4 100644 (file)
--- a/src/time/timer_create.c
+++ b/src/time/timer_create.c
@@ -11,7 +11,6 @@ struct ksigevent {
 struct start_args {
        pthread_barrier_t b;
        struct sigevent *sev;
-       timer_t t;
 };
 
 static void sighandler(int sig, siginfo_t *si, void *ctx)
@@ -26,30 +25,21 @@ static void sighandler(int sig, siginfo_t *si, void *ctx)
        pthread_setcancelstate(st, 0);
 }
 
-static void killtimer(void *arg)
-{
-       timer_t t = arg;
-       if (t->timerid >= 0) __syscall(SYS_timer_delete, t->timerid);
-}
-
 static void *start(void *arg)
 {
        pthread_t self = __pthread_self();
        struct start_args *args = arg;
-       struct __timer t = { .timerid = -1 };
 
        /* Reuse no-longer-needed thread structure fields to avoid
         * needing the timer address in the signal handler. */
        self->start = (void *(*)(void *))args->sev->sigev_notify_function;
        self->start_arg = args->sev->sigev_value.sival_ptr;
-       args->t = &t;
+       self->result = (void *)-1;
 
-       pthread_cleanup_push(killtimer, &t);
        pthread_barrier_wait(&args->b);
        pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, 0);
        /* Loop on async-signal-safe cancellation point */
        for (;;) sleep(1);
-       pthread_cleanup_pop(1);
        return 0;
 }
 
@@ -79,11 +69,7 @@ int timer_create(clockid_t clk, struct sigevent *evp, timer_t *res)
                ksev.sigev_tid = 0;
                if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0)
                        return -1;
-               if (!(t = calloc(1, sizeof *t))) {
-                       syscall(SYS_timer_delete, timerid);
-                       return -1;
-               }
-               t->timerid = timerid;
+               *res = (void *)(2*timerid+1);
                break;
        case SIGEV_THREAD:
                if (!libc.sigtimer) libc.sigtimer = sighandler;
@@ -105,19 +91,17 @@ int timer_create(clockid_t clk, struct sigevent *evp, timer_t *res)
                ksev.sigev_tid = td->tid;
                r = syscall(SYS_timer_create, clk, &ksev, &timerid);
                pthread_barrier_wait(&args.b);
-               t = args.t;
                if (r < 0) {
                        pthread_cancel(td);
                        return -1;
                }
-               t->timerid = timerid;
-               t->thread = td;
+               td->result = (void *)timerid;
+               *res = td;
                break;
        default:
                errno = EINVAL;
                return -1;
        }
 
-       *res = t;
        return 0;
 }

diff --git a/src/time/timer_delete.c b/src/time/timer_delete.c
index caf0489..437de2e 100644 (file)
--- a/src/time/timer_delete.c
+++ b/src/time/timer_delete.c
@@ -3,10 +3,11 @@
 
 int timer_delete(timer_t t)
 {
-       if (t->thread) pthread_cancel(t->thread);
-       else {
-               __syscall(SYS_timer_delete, t->timerid);
-               free(t);
-       }
-       return 0;
+       pthread_t td = 0;
+       int r;
+       if ((uintptr_t)t & 1) t = (void *)((unsigned long)t / 2);
+       else td = t, t = td->result;
+       r = __syscall(SYS_timer_delete, (long)t);
+       if (td) pthread_cancel(td);
+       return r;
 }

diff --git a/src/time/timer_getoverrun.c b/src/time/timer_getoverrun.c
index 1334e45..fa7715b 100644 (file)
--- a/src/time/timer_getoverrun.c
+++ b/src/time/timer_getoverrun.c
@@ -3,5 +3,7 @@
 
 int timer_getoverrun(timer_t t)
 {
-       return syscall(SYS_timer_getoverrun, t->timerid);
+       if ((uintptr_t)t & 1) t = (void *)((unsigned long)t / 2);
+       else t = ((pthread_t)t)->result;
+       return syscall(SYS_timer_getoverrun, (long)t);
 }

diff --git a/src/time/timer_gettime.c b/src/time/timer_gettime.c
index 3d3156a..2320873 100644 (file)
--- a/src/time/timer_gettime.c
+++ b/src/time/timer_gettime.c
@@ -3,5 +3,7 @@
 
 int timer_gettime(timer_t t, struct itimerspec *val)
 {
-       return syscall(SYS_timer_gettime, t->timerid, val);
+       if ((uintptr_t)t & 1) t = (void *)((unsigned long)t / 2);
+       else t = ((pthread_t)t)->result;
+       return syscall(SYS_timer_gettime, (long)t, val);
 }

diff --git a/src/time/timer_settime.c b/src/time/timer_settime.c
index d109570..00708f0 100644 (file)
--- a/src/time/timer_settime.c
+++ b/src/time/timer_settime.c
@@ -3,5 +3,7 @@
 
 int timer_settime(timer_t t, int flags, const struct itimerspec *val, struct itimerspec *old)
 {
-       return syscall(SYS_timer_settime, t->timerid, flags, val, old);
+       if ((uintptr_t)t & 1) t = (void *)((unsigned long)t / 2);
+       else t = ((pthread_t)t)->result;
+       return syscall(SYS_timer_settime, (long)t, flags, val, old);
 }