[S390] tape: deadlock on system work queue
The 34xx and 3590 tape driver uses the system work queue to defer work from the interrupt function to process context, e.g. a medium sense after an unsolicited interrupt. The tape commands started by the work handler need to be asynchronous, otherwise a deadlock on the system work queue can occur. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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@ -280,6 +280,14 @@ tape_do_io_free(struct tape_device *device, struct tape_request *request)
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return rc;
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}
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static inline void
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tape_do_io_async_free(struct tape_device *device, struct tape_request *request)
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{
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request->callback = (void *) tape_free_request;
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request->callback_data = NULL;
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tape_do_io_async(device, request);
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}
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extern int tape_oper_handler(int irq, int status);
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extern void tape_noper_handler(int irq, int status);
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extern int tape_open(struct tape_device *);
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@ -53,23 +53,11 @@ static void tape_34xx_delete_sbid_from(struct tape_device *, int);
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* Medium sense for 34xx tapes. There is no 'real' medium sense call.
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* So we just do a normal sense.
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*/
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static int
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tape_34xx_medium_sense(struct tape_device *device)
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static void __tape_34xx_medium_sense(struct tape_request *request)
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{
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struct tape_request *request;
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unsigned char *sense;
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int rc;
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struct tape_device *device = request->device;
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unsigned char *sense;
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request = tape_alloc_request(1, 32);
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if (IS_ERR(request)) {
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DBF_EXCEPTION(6, "MSEN fail\n");
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return PTR_ERR(request);
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}
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request->op = TO_MSEN;
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tape_ccw_end(request->cpaddr, SENSE, 32, request->cpdata);
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rc = tape_do_io_interruptible(device, request);
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if (request->rc == 0) {
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sense = request->cpdata;
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@ -88,15 +76,47 @@ tape_34xx_medium_sense(struct tape_device *device)
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device->tape_generic_status |= GMT_WR_PROT(~0);
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else
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device->tape_generic_status &= ~GMT_WR_PROT(~0);
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} else {
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} else
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DBF_EVENT(4, "tape_34xx: medium sense failed with rc=%d\n",
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request->rc);
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}
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tape_free_request(request);
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}
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static int tape_34xx_medium_sense(struct tape_device *device)
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{
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struct tape_request *request;
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int rc;
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request = tape_alloc_request(1, 32);
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if (IS_ERR(request)) {
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DBF_EXCEPTION(6, "MSEN fail\n");
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return PTR_ERR(request);
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}
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request->op = TO_MSEN;
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tape_ccw_end(request->cpaddr, SENSE, 32, request->cpdata);
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rc = tape_do_io_interruptible(device, request);
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__tape_34xx_medium_sense(request);
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return rc;
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}
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static void tape_34xx_medium_sense_async(struct tape_device *device)
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{
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struct tape_request *request;
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request = tape_alloc_request(1, 32);
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if (IS_ERR(request)) {
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DBF_EXCEPTION(6, "MSEN fail\n");
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return;
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}
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request->op = TO_MSEN;
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tape_ccw_end(request->cpaddr, SENSE, 32, request->cpdata);
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request->callback = (void *) __tape_34xx_medium_sense;
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request->callback_data = NULL;
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tape_do_io_async(device, request);
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}
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struct tape_34xx_work {
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struct tape_device *device;
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enum tape_op op;
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@ -109,6 +129,9 @@ struct tape_34xx_work {
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* is inserted but cannot call tape_do_io* from an interrupt context.
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* Maybe that's useful for other actions we want to start from the
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* interrupt handler.
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* Note: the work handler is called by the system work queue. The tape
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* commands started by the handler need to be asynchrounous, otherwise
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* a deadlock can occur e.g. in case of a deferred cc=1 (see __tape_do_irq).
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*/
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static void
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tape_34xx_work_handler(struct work_struct *work)
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@ -119,7 +142,7 @@ tape_34xx_work_handler(struct work_struct *work)
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switch(p->op) {
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case TO_MSEN:
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tape_34xx_medium_sense(device);
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tape_34xx_medium_sense_async(device);
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break;
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default:
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DBF_EVENT(3, "T34XX: internal error: unknown work\n");
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@ -329,17 +329,17 @@ out:
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/*
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* Enable encryption
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*/
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static int tape_3592_enable_crypt(struct tape_device *device)
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static struct tape_request *__tape_3592_enable_crypt(struct tape_device *device)
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{
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struct tape_request *request;
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char *data;
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DBF_EVENT(6, "tape_3592_enable_crypt\n");
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if (!crypt_supported(device))
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return -ENOSYS;
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return ERR_PTR(-ENOSYS);
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request = tape_alloc_request(2, 72);
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if (IS_ERR(request))
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return PTR_ERR(request);
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return request;
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data = request->cpdata;
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memset(data,0,72);
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@ -354,23 +354,42 @@ static int tape_3592_enable_crypt(struct tape_device *device)
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request->op = TO_CRYPT_ON;
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tape_ccw_cc(request->cpaddr, MODE_SET_CB, 36, data);
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tape_ccw_end(request->cpaddr + 1, MODE_SET_CB, 36, data + 36);
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return request;
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}
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static int tape_3592_enable_crypt(struct tape_device *device)
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{
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struct tape_request *request;
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request = __tape_3592_enable_crypt(device);
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if (IS_ERR(request))
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return PTR_ERR(request);
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return tape_do_io_free(device, request);
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}
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static void tape_3592_enable_crypt_async(struct tape_device *device)
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{
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struct tape_request *request;
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request = __tape_3592_enable_crypt(device);
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if (!IS_ERR(request))
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tape_do_io_async_free(device, request);
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}
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/*
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* Disable encryption
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*/
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static int tape_3592_disable_crypt(struct tape_device *device)
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static struct tape_request *__tape_3592_disable_crypt(struct tape_device *device)
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{
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struct tape_request *request;
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char *data;
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DBF_EVENT(6, "tape_3592_disable_crypt\n");
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if (!crypt_supported(device))
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return -ENOSYS;
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return ERR_PTR(-ENOSYS);
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request = tape_alloc_request(2, 72);
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if (IS_ERR(request))
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return PTR_ERR(request);
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return request;
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data = request->cpdata;
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memset(data,0,72);
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@ -383,9 +402,28 @@ static int tape_3592_disable_crypt(struct tape_device *device)
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tape_ccw_cc(request->cpaddr, MODE_SET_CB, 36, data);
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tape_ccw_end(request->cpaddr + 1, MODE_SET_CB, 36, data + 36);
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return request;
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}
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static int tape_3592_disable_crypt(struct tape_device *device)
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{
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struct tape_request *request;
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request = __tape_3592_disable_crypt(device);
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if (IS_ERR(request))
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return PTR_ERR(request);
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return tape_do_io_free(device, request);
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}
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static void tape_3592_disable_crypt_async(struct tape_device *device)
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{
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struct tape_request *request;
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request = __tape_3592_disable_crypt(device);
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if (!IS_ERR(request))
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tape_do_io_async_free(device, request);
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}
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/*
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* IOCTL: Set encryption status
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*/
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@ -457,8 +495,7 @@ tape_3590_ioctl(struct tape_device *device, unsigned int cmd, unsigned long arg)
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/*
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* SENSE Medium: Get Sense data about medium state
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*/
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static int
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tape_3590_sense_medium(struct tape_device *device)
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static int tape_3590_sense_medium(struct tape_device *device)
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{
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struct tape_request *request;
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@ -470,6 +507,18 @@ tape_3590_sense_medium(struct tape_device *device)
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return tape_do_io_free(device, request);
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}
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static void tape_3590_sense_medium_async(struct tape_device *device)
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{
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struct tape_request *request;
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request = tape_alloc_request(1, 128);
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if (IS_ERR(request))
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return;
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request->op = TO_MSEN;
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tape_ccw_end(request->cpaddr, MEDIUM_SENSE, 128, request->cpdata);
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tape_do_io_async_free(device, request);
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}
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/*
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* MTTELL: Tell block. Return the number of block relative to current file.
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*/
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@ -546,15 +595,14 @@ tape_3590_read_opposite(struct tape_device *device,
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* 2. The attention msg is written to the "read subsystem data" buffer.
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* In this case we probably should print it to the console.
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*/
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static int
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tape_3590_read_attmsg(struct tape_device *device)
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static void tape_3590_read_attmsg_async(struct tape_device *device)
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{
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struct tape_request *request;
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char *buf;
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request = tape_alloc_request(3, 4096);
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if (IS_ERR(request))
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return PTR_ERR(request);
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return;
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request->op = TO_READ_ATTMSG;
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buf = request->cpdata;
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buf[0] = PREP_RD_SS_DATA;
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@ -562,12 +610,15 @@ tape_3590_read_attmsg(struct tape_device *device)
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tape_ccw_cc(request->cpaddr, PERFORM_SS_FUNC, 12, buf);
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tape_ccw_cc(request->cpaddr + 1, READ_SS_DATA, 4096 - 12, buf + 12);
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tape_ccw_end(request->cpaddr + 2, NOP, 0, NULL);
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return tape_do_io_free(device, request);
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tape_do_io_async_free(device, request);
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}
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/*
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* These functions are used to schedule follow-up actions from within an
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* interrupt context (like unsolicited interrupts).
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* Note: the work handler is called by the system work queue. The tape
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* commands started by the handler need to be asynchrounous, otherwise
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* a deadlock can occur e.g. in case of a deferred cc=1 (see __tape_do_irq).
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*/
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struct work_handler_data {
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struct tape_device *device;
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@ -583,16 +634,16 @@ tape_3590_work_handler(struct work_struct *work)
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switch (p->op) {
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case TO_MSEN:
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tape_3590_sense_medium(p->device);
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tape_3590_sense_medium_async(p->device);
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break;
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case TO_READ_ATTMSG:
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tape_3590_read_attmsg(p->device);
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tape_3590_read_attmsg_async(p->device);
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break;
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case TO_CRYPT_ON:
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tape_3592_enable_crypt(p->device);
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tape_3592_enable_crypt_async(p->device);
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break;
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case TO_CRYPT_OFF:
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tape_3592_disable_crypt(p->device);
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tape_3592_disable_crypt_async(p->device);
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break;
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default:
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DBF_EVENT(3, "T3590: work handler undefined for "
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