diff options
| -rw-r--r-- | libports/manage-multithread.c | 53 |
1 files changed, 18 insertions, 35 deletions
diff --git a/libports/manage-multithread.c b/libports/manage-multithread.c index 0c2da005..842665a5 100644 --- a/libports/manage-multithread.c +++ b/libports/manage-multithread.c @@ -91,9 +91,12 @@ ports_manage_port_operations_multithread (struct port_bucket *bucket, int global_timeout, void (*hook)()) { - volatile unsigned int nreqthreads; - volatile unsigned int totalthreads; - pthread_spinlock_t lock = PTHREAD_SPINLOCK_INITIALIZER; + /* totalthreads is the number of total threads created. nreqthreads + is the number of threads not currently servicing any client. The + initial values account for the main thread. */ + unsigned int totalthreads = 1; + unsigned int nreqthreads = 1; + pthread_attr_t attr; auto void * thread_function (void *); @@ -120,30 +123,22 @@ ports_manage_port_operations_multithread (struct port_bucket *bucket, /* msgt_unused = */ 0 }; - pthread_spin_lock (&lock); - assert (nreqthreads); - nreqthreads--; - if (nreqthreads != 0) - pthread_spin_unlock (&lock); - else + if (__atomic_sub_fetch (&nreqthreads, 1, __ATOMIC_RELAXED) == 0) /* No thread would be listening for requests, spawn one. */ { pthread_t pthread_id; error_t err; - totalthreads++; - nreqthreads++; - pthread_spin_unlock (&lock); + __atomic_add_fetch (&totalthreads, 1, __ATOMIC_RELAXED); + __atomic_add_fetch (&nreqthreads, 1, __ATOMIC_RELAXED); err = pthread_create (&pthread_id, &attr, thread_function, NULL); if (!err) pthread_detach (pthread_id); else { - pthread_spin_lock (&lock); - totalthreads--; - nreqthreads--; - pthread_spin_unlock (&lock); + __atomic_sub_fetch (&totalthreads, 1, __ATOMIC_RELAXED); + __atomic_sub_fetch (&nreqthreads, 1, __ATOMIC_RELAXED); /* There is not much we can do at this point. The code and design of the Hurd servers just don't handle thread creation failure. */ @@ -189,9 +184,7 @@ ports_manage_port_operations_multithread (struct port_bucket *bucket, status = 1; } - pthread_spin_lock (&lock); - nreqthreads++; - pthread_spin_unlock (&lock); + __atomic_add_fetch (&nreqthreads, 1, __ATOMIC_RELAXED); return status; } @@ -203,8 +196,7 @@ ports_manage_port_operations_multithread (struct port_bucket *bucket, int timeout; error_t err; - /* No need to lock as an approximation is sufficient. */ - adjust_priority (totalthreads); + adjust_priority (__atomic_load_n (&totalthreads, __ATOMIC_RELAXED)); if (hook) (*hook) (); @@ -224,30 +216,21 @@ ports_manage_port_operations_multithread (struct port_bucket *bucket, if (master) { - pthread_spin_lock (&lock); - if (totalthreads != 1) - { - pthread_spin_unlock (&lock); - goto startover; - } + if (__atomic_load_n (&totalthreads, __ATOMIC_RELAXED) != 1) + goto startover; } else { - pthread_spin_lock (&lock); - if (nreqthreads == 1) + if (__atomic_sub_fetch (&nreqthreads, 1, __ATOMIC_RELAXED) == 0) { /* No other thread is listening for requests, continue. */ - pthread_spin_unlock (&lock); + __atomic_add_fetch (&nreqthreads, 1, __ATOMIC_RELAXED); goto startover; } - nreqthreads--; - totalthreads--; - pthread_spin_unlock (&lock); + __atomic_sub_fetch (&totalthreads, 1, __ATOMIC_RELAXED); } return NULL; } - nreqthreads = 1; - totalthreads = 1; thread_function ((void *) 1); } |