diff options
Diffstat (limited to 'drivers/s390/crypto/ap_bus.c')
| -rw-r--r-- | drivers/s390/crypto/ap_bus.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c index ebc3fe2a7f40..f3253cb27a76 100644 --- a/drivers/s390/crypto/ap_bus.c +++ b/drivers/s390/crypto/ap_bus.c @@ -107,6 +107,7 @@ debug_info_t *ap_dbf_info; static bool ap_scan_bus(void); static bool ap_scan_bus_result; /* result of last ap_scan_bus() */ static DEFINE_MUTEX(ap_scan_bus_mutex); /* mutex ap_scan_bus() invocations */ +static struct task_struct *ap_scan_bus_task; /* thread holding the scan mutex */ static atomic64_t ap_scan_bus_count; /* counter ap_scan_bus() invocations */ static int ap_scan_bus_time = AP_CONFIG_TIME; static struct timer_list ap_scan_bus_timer; @@ -1000,11 +1001,25 @@ bool ap_bus_force_rescan(void) if (scan_counter <= 0) goto out; + /* + * There is one unlikely but nevertheless valid scenario where the + * thread holding the mutex may try to send some crypto load but + * all cards are offline so a rescan is triggered which causes + * a recursive call of ap_bus_force_rescan(). A simple return if + * the mutex is already locked by this thread solves this. + */ + if (mutex_is_locked(&ap_scan_bus_mutex)) { + if (ap_scan_bus_task == current) + goto out; + } + /* Try to acquire the AP scan bus mutex */ if (mutex_trylock(&ap_scan_bus_mutex)) { /* mutex acquired, run the AP bus scan */ + ap_scan_bus_task = current; ap_scan_bus_result = ap_scan_bus(); rc = ap_scan_bus_result; + ap_scan_bus_task = NULL; mutex_unlock(&ap_scan_bus_mutex); goto out; } @@ -2277,7 +2292,9 @@ static void ap_scan_bus_wq_callback(struct work_struct *unused) * system_long_wq which invokes this function here again. */ if (mutex_trylock(&ap_scan_bus_mutex)) { + ap_scan_bus_task = current; ap_scan_bus_result = ap_scan_bus(); + ap_scan_bus_task = NULL; mutex_unlock(&ap_scan_bus_mutex); } } |