scsi: mpt3sas: Maintain owner of buffer through UniqueID

Application A has registered a diag buffer and looking for particular event
to happen to release & read the trace buffer. Meanwhile application B has
unregistered the diag buffer and now Application A can't get the required
diag buffer. So proper diag buffer ownership is missing.

Each application has to maintain its own Unique ID. Now driver has to save
the Application's UniqueID for each diag buffer type when diag buffer is
registered. And driver has to allow 'release', 'read' & 'unregister' diag
commands only if application's UniqueID matches with saved UniqueID for the
corresponding diag buffer type.

When diag buffer is registered by the driver, then the UniqueID saved by
the driver is "BRCM" (i.e. 0x4252434D) for SAS3 and above generations HBA
devices. For SAS2 HBAs, driver keeps the legacy UniqueID 0x07075900 for
maintaining compatibility with the legacy SAS2 application and this
improvement won't be applicable for SAS2 HBA devices.

Any application can own the buffer registered by the driver by sending
diag register request to driver with same buffer type and size
(Application can get the buffer size by sending 'query' command). Then
driver changes the ownership of the buffer by saving application's
UniqueID for that corresponding buffer type.

Also, application can re-register the diag buffer with same size without
un-registering it, but diag buffer should be released before re-registering
it. By allowing this, driver no need to deallocate and allocate a new
buffer for re-register command, same buffer can be re-used.

Link: https://lore.kernel.org/r/1568379890-18347-6-git-send-email-sreekanth.reddy@broadcom.comSigned-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mpt3sas/mpt3sas_ctl.c

@@ -1491,6 +1491,26 @@ _ctl_diag_capability(struct MPT3SAS_ADAPTER *ioc, u8 buffer_type)
 	return rc;
 }
 
+/**
+ * _ctl_diag_get_bufftype - return diag buffer type
+ *              either TRACE, SNAPSHOT, or EXTENDED
+ * @ioc: per adapter object
+ * @unique_id: specifies the unique_id for the buffer
+ *
+ * returns MPT3_DIAG_UID_NOT_FOUND if the id not found
+ */
+static u8
+_ctl_diag_get_bufftype(struct MPT3SAS_ADAPTER *ioc, u32 unique_id)
+{
+	u8  index;
+
+	for (index = 0; index < MPI2_DIAG_BUF_TYPE_COUNT; index++) {
+		if (ioc->unique_id[index] == unique_id)
+			return index;
+	}
+
+	return MPT3_DIAG_UID_NOT_FOUND;
+}
 
 /**
  * _ctl_diag_register_2 - wrapper for registering diag buffer support
@@ -1538,11 +1558,65 @@ _ctl_diag_register_2(struct MPT3SAS_ADAPTER *ioc,
 		return -EPERM;
 	}
 
+	if (diag_register->unique_id == 0) {
+		ioc_err(ioc,
+		    "%s: Invalid UID(0x%08x), buffer_type(0x%02x)\n", __func__,
+		    diag_register->unique_id, buffer_type);
+		return -EINVAL;
+	}
+
 	if (ioc->diag_buffer_status[buffer_type] &
 	    MPT3_DIAG_BUFFER_IS_REGISTERED) {
-		ioc_err(ioc, "%s: already has a registered buffer for buffer_type(0x%02x)\n",
-			__func__, buffer_type);
-		return -EINVAL;
+		/*
+		 * If driver posts buffer initially, then an application wants
+		 * to Register that buffer (own it) without Releasing first,
+		 * the application Register command MUST have the same buffer
+		 * type and size in the Register command (obtained from the
+		 * Query command). Otherwise that Register command will be
+		 * failed. If the application has released the buffer but wants
+		 * to re-register it, it should be allowed as long as the
+		 * Unique-Id/Size match.
+		 */
+
+		if (ioc->unique_id[buffer_type] == MPT3DIAGBUFFUNIQUEID &&
+		    ioc->diag_buffer_sz[buffer_type] ==
+		    diag_register->requested_buffer_size) {
+
+			if (!(ioc->diag_buffer_status[buffer_type] &
+			     MPT3_DIAG_BUFFER_IS_RELEASED)) {
+				dctlprintk(ioc, ioc_info(ioc,
+				    "%s: diag_buffer (%d) ownership changed. old-ID(0x%08x), new-ID(0x%08x)\n",
+				    __func__, buffer_type,
+				    ioc->unique_id[buffer_type],
+				    diag_register->unique_id));
+
+				/*
+				 * Application wants to own the buffer with
+				 * the same size.
+				 */
+				ioc->unique_id[buffer_type] =
+				    diag_register->unique_id;
+				rc = 0; /* success */
+				goto out;
+			}
+		} else if (ioc->unique_id[buffer_type] !=
+		    MPT3DIAGBUFFUNIQUEID) {
+			if (ioc->unique_id[buffer_type] !=
+			    diag_register->unique_id ||
+			    ioc->diag_buffer_sz[buffer_type] !=
+			    diag_register->requested_buffer_size ||
+			    !(ioc->diag_buffer_status[buffer_type] &
+			    MPT3_DIAG_BUFFER_IS_RELEASED)) {
+				ioc_err(ioc,
+				    "%s: already has a registered buffer for buffer_type(0x%02x)\n",
+				    __func__, buffer_type);
+				return -EINVAL;
+			}
+		} else {
+			ioc_err(ioc, "%s: already has a registered buffer for buffer_type(0x%02x)\n",
+			    __func__, buffer_type);
+			return -EINVAL;
+		}
 	}
 
 	if (diag_register->requested_buffer_size % 4)  {
@@ -1689,7 +1763,9 @@ mpt3sas_enable_diag_buffer(struct MPT3SAS_ADAPTER *ioc, u8 bits_to_register)
 		ioc->diag_trigger_master.MasterData =
 		    (MASTER_TRIGGER_FW_FAULT + MASTER_TRIGGER_ADAPTER_RESET);
 		diag_register.buffer_type = MPI2_DIAG_BUF_TYPE_TRACE;
-		diag_register.unique_id = 0x7075900;
+		diag_register.unique_id =
+		    (ioc->hba_mpi_version_belonged == MPI2_VERSION) ?
+		    (MPT2DIAGBUFFUNIQUEID):(MPT3DIAGBUFFUNIQUEID);
 
 		if (trace_buff_size != 0) {
 			diag_register.requested_buffer_size = trace_buff_size;
@@ -1815,7 +1891,13 @@ _ctl_diag_unregister(struct MPT3SAS_ADAPTER *ioc, void __user *arg)
 	dctlprintk(ioc, ioc_info(ioc, "%s\n",
 				 __func__));
 
-	buffer_type = karg.unique_id & 0x000000ff;
+	buffer_type = _ctl_diag_get_bufftype(ioc, karg.unique_id);
+	if (buffer_type == MPT3_DIAG_UID_NOT_FOUND) {
+		ioc_err(ioc, "%s: buffer with unique_id(0x%08x) not found\n",
+		    __func__, karg.unique_id);
+		return -EINVAL;
+	}
+
 	if (!_ctl_diag_capability(ioc, buffer_type)) {
 		ioc_err(ioc, "%s: doesn't have capability for buffer_type(0x%02x)\n",
 			__func__, buffer_type);
@@ -1899,7 +1981,7 @@ _ctl_diag_query(struct MPT3SAS_ADAPTER *ioc, void __user *arg)
 		return -EINVAL;
 	}
 
-	if (karg.unique_id & 0xffffff00) {
+	if (karg.unique_id) {
 		if (karg.unique_id != ioc->unique_id[buffer_type]) {
 			ioc_err(ioc, "%s: unique_id(0x%08x) is not registered\n",
 				__func__, karg.unique_id);
@@ -2065,7 +2147,13 @@ _ctl_diag_release(struct MPT3SAS_ADAPTER *ioc, void __user *arg)
 	dctlprintk(ioc, ioc_info(ioc, "%s\n",
 				 __func__));
 
-	buffer_type = karg.unique_id & 0x000000ff;
+	buffer_type = _ctl_diag_get_bufftype(ioc, karg.unique_id);
+	if (buffer_type == MPT3_DIAG_UID_NOT_FOUND) {
+		ioc_err(ioc, "%s: buffer with unique_id(0x%08x) not found\n",
+		    __func__, karg.unique_id);
+		return -EINVAL;
+	}
+
 	if (!_ctl_diag_capability(ioc, buffer_type)) {
 		ioc_err(ioc, "%s: doesn't have capability for buffer_type(0x%02x)\n",
 			__func__, buffer_type);
@@ -2149,7 +2237,13 @@ _ctl_diag_read_buffer(struct MPT3SAS_ADAPTER *ioc, void __user *arg)
 	dctlprintk(ioc, ioc_info(ioc, "%s\n",
 				 __func__));
 
-	buffer_type = karg.unique_id & 0x000000ff;
+	buffer_type = _ctl_diag_get_bufftype(ioc, karg.unique_id);
+	if (buffer_type == MPT3_DIAG_UID_NOT_FOUND) {
+		ioc_err(ioc, "%s: buffer with unique_id(0x%08x) not found\n",
+		    __func__, karg.unique_id);
+		return -EINVAL;
+	}
+
 	if (!_ctl_diag_capability(ioc, buffer_type)) {
 		ioc_err(ioc, "%s: doesn't have capability for buffer_type(0x%02x)\n",
 			__func__, buffer_type);
@@ -3202,7 +3296,9 @@ host_trace_buffer_enable_store(struct device *cdev,
 		} else
 			diag_register.requested_buffer_size = (1024 * 1024);
 
-		diag_register.unique_id = 0x7075900;
+		diag_register.unique_id =
+		    (ioc->hba_mpi_version_belonged == MPI2_VERSION) ?
+		    (MPT2DIAGBUFFUNIQUEID):(MPT3DIAGBUFFUNIQUEID);
 		ioc->diag_buffer_status[MPI2_DIAG_BUF_TYPE_TRACE] = 0;
 		_ctl_diag_register_2(ioc,  &diag_register);
 	} else if (!strcmp(str, "release")) {

drivers/scsi/mpt3sas/mpt3sas_ctl.h

@@ -95,6 +95,14 @@
 #define MPT3DIAGREADBUFFER _IOWR(MPT3_MAGIC_NUMBER, 30, \
 	struct mpt3_diag_read_buffer)
 
+/* Trace Buffer default UniqueId */
+#define MPT2DIAGBUFFUNIQUEID (0x07075900)
+#define MPT3DIAGBUFFUNIQUEID (0x4252434D)
+
+/* UID not found */
+#define MPT3_DIAG_UID_NOT_FOUND (0xFF)
+
+
 /**
  * struct mpt3_ioctl_header - main header structure
  * @ioc_number -  IOC unit number