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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2011-03-03 17:56:07 +0100
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2011-03-03 17:56:14 +0100
commit0c2bd9b24e73287aa4ee87844c847205e0da8a9b (patch)
tree4e56fae8cb7f8dcbc022771436e573c5c12b94fb /drivers/s390/char/tape_3590.c
parentb652277b09d3d030cb074cc6a98ba80b34244c03 (diff)
[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>
Diffstat (limited to 'drivers/s390/char/tape_3590.c')
-rw-r--r--drivers/s390/char/tape_3590.c83
1 files changed, 67 insertions, 16 deletions
diff --git a/drivers/s390/char/tape_3590.c b/drivers/s390/char/tape_3590.c
index fbe361fcd2c0..de2e99e0a71b 100644
--- a/drivers/s390/char/tape_3590.c
+++ b/drivers/s390/char/tape_3590.c
@@ -329,17 +329,17 @@ out:
/*
* Enable encryption
*/
-static int tape_3592_enable_crypt(struct tape_device *device)
+static struct tape_request *__tape_3592_enable_crypt(struct tape_device *device)
{
struct tape_request *request;
char *data;
DBF_EVENT(6, "tape_3592_enable_crypt\n");
if (!crypt_supported(device))
- return -ENOSYS;
+ return ERR_PTR(-ENOSYS);
request = tape_alloc_request(2, 72);
if (IS_ERR(request))
- return PTR_ERR(request);
+ return request;
data = request->cpdata;
memset(data,0,72);
@@ -354,23 +354,42 @@ static int tape_3592_enable_crypt(struct tape_device *device)
request->op = TO_CRYPT_ON;
tape_ccw_cc(request->cpaddr, MODE_SET_CB, 36, data);
tape_ccw_end(request->cpaddr + 1, MODE_SET_CB, 36, data + 36);
+ return request;
+}
+
+static int tape_3592_enable_crypt(struct tape_device *device)
+{
+ struct tape_request *request;
+
+ request = __tape_3592_enable_crypt(device);
+ if (IS_ERR(request))
+ return PTR_ERR(request);
return tape_do_io_free(device, request);
}
+static void tape_3592_enable_crypt_async(struct tape_device *device)
+{
+ struct tape_request *request;
+
+ request = __tape_3592_enable_crypt(device);
+ if (!IS_ERR(request))
+ tape_do_io_async_free(device, request);
+}
+
/*
* Disable encryption
*/
-static int tape_3592_disable_crypt(struct tape_device *device)
+static struct tape_request *__tape_3592_disable_crypt(struct tape_device *device)
{
struct tape_request *request;
char *data;
DBF_EVENT(6, "tape_3592_disable_crypt\n");
if (!crypt_supported(device))
- return -ENOSYS;
+ return ERR_PTR(-ENOSYS);
request = tape_alloc_request(2, 72);
if (IS_ERR(request))
- return PTR_ERR(request);
+ return request;
data = request->cpdata;
memset(data,0,72);
@@ -383,9 +402,28 @@ static int tape_3592_disable_crypt(struct tape_device *device)
tape_ccw_cc(request->cpaddr, MODE_SET_CB, 36, data);
tape_ccw_end(request->cpaddr + 1, MODE_SET_CB, 36, data + 36);
+ return request;
+}
+
+static int tape_3592_disable_crypt(struct tape_device *device)
+{
+ struct tape_request *request;
+
+ request = __tape_3592_disable_crypt(device);
+ if (IS_ERR(request))
+ return PTR_ERR(request);
return tape_do_io_free(device, request);
}
+static void tape_3592_disable_crypt_async(struct tape_device *device)
+{
+ struct tape_request *request;
+
+ request = __tape_3592_disable_crypt(device);
+ if (!IS_ERR(request))
+ tape_do_io_async_free(device, request);
+}
+
/*
* IOCTL: Set encryption status
*/
@@ -457,8 +495,7 @@ tape_3590_ioctl(struct tape_device *device, unsigned int cmd, unsigned long arg)
/*
* SENSE Medium: Get Sense data about medium state
*/
-static int
-tape_3590_sense_medium(struct tape_device *device)
+static int tape_3590_sense_medium(struct tape_device *device)
{
struct tape_request *request;
@@ -470,6 +507,18 @@ tape_3590_sense_medium(struct tape_device *device)
return tape_do_io_free(device, request);
}
+static void tape_3590_sense_medium_async(struct tape_device *device)
+{
+ struct tape_request *request;
+
+ request = tape_alloc_request(1, 128);
+ if (IS_ERR(request))
+ return;
+ request->op = TO_MSEN;
+ tape_ccw_end(request->cpaddr, MEDIUM_SENSE, 128, request->cpdata);
+ tape_do_io_async_free(device, request);
+}
+
/*
* MTTELL: Tell block. Return the number of block relative to current file.
*/
@@ -546,15 +595,14 @@ tape_3590_read_opposite(struct tape_device *device,
* 2. The attention msg is written to the "read subsystem data" buffer.
* In this case we probably should print it to the console.
*/
-static int
-tape_3590_read_attmsg(struct tape_device *device)
+static void tape_3590_read_attmsg_async(struct tape_device *device)
{
struct tape_request *request;
char *buf;
request = tape_alloc_request(3, 4096);
if (IS_ERR(request))
- return PTR_ERR(request);
+ return;
request->op = TO_READ_ATTMSG;
buf = request->cpdata;
buf[0] = PREP_RD_SS_DATA;
@@ -562,12 +610,15 @@ tape_3590_read_attmsg(struct tape_device *device)
tape_ccw_cc(request->cpaddr, PERFORM_SS_FUNC, 12, buf);
tape_ccw_cc(request->cpaddr + 1, READ_SS_DATA, 4096 - 12, buf + 12);
tape_ccw_end(request->cpaddr + 2, NOP, 0, NULL);
- return tape_do_io_free(device, request);
+ tape_do_io_async_free(device, request);
}
/*
* These functions are used to schedule follow-up actions from within an
* interrupt context (like unsolicited interrupts).
+ * Note: the work handler is called by the system work queue. The tape
+ * commands started by the handler need to be asynchrounous, otherwise
+ * a deadlock can occur e.g. in case of a deferred cc=1 (see __tape_do_irq).
*/
struct work_handler_data {
struct tape_device *device;
@@ -583,16 +634,16 @@ tape_3590_work_handler(struct work_struct *work)
switch (p->op) {
case TO_MSEN:
- tape_3590_sense_medium(p->device);
+ tape_3590_sense_medium_async(p->device);
break;
case TO_READ_ATTMSG:
- tape_3590_read_attmsg(p->device);
+ tape_3590_read_attmsg_async(p->device);
break;
case TO_CRYPT_ON:
- tape_3592_enable_crypt(p->device);
+ tape_3592_enable_crypt_async(p->device);
break;
case TO_CRYPT_OFF:
- tape_3592_disable_crypt(p->device);
+ tape_3592_disable_crypt_async(p->device);
break;
default:
DBF_EVENT(3, "T3590: work handler undefined for "