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hide EH backup data outside the scsi_cmnd

PATCH New Christoph Hellwig 1 participant 1 message Jul 8, 2006

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PATCH 2/2 hide EH backup data outside the scsi_cmnd

Currently struct scsi_cmnd has various fields that are used to backup original data after the corresponding fields have been overridden for EH commands. This means drivers can easily get at it and misuse it. Due to the old_ naming this doesn't happen for most of them, but two that have different names have been used wrong a lot (see previous patch). Another downside is that they unessecarily bloat the scsi_cmnd size.

This patch moves them onstack in scsi_send_eh_cmnd to fix those two issues aswell as allowing future EH fixes like moving the EH command submissions to use SG lists like everything else.

drivers/scsi/scsi_error.c +89 -121
Index: scsi-misc-2.6/drivers/scsi/scsi_error.c
===================================================================
@@ -460,19 +460,67 @@
  * Return value:
  *    SUCCESS or FAILED or NEEDS_RETRY
  **/
-static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, int timeout)
+static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, int timeout, int copy_sense)
 {
 	struct scsi_device *sdev = scmd->device;
 	struct Scsi_Host *shost = sdev->host;
+	int old_result = scmd->result;
 	DECLARE_COMPLETION(done);
 	unsigned long timeleft;
 	unsigned long flags;
+	unsigned char old_cmnd[MAX_COMMAND_SIZE];
+	enum dma_data_direction old_data_direction;
+	unsigned short old_use_sg;
+	unsigned char old_cmd_len;
+	unsigned old_bufflen;
+	void *old_buffer;
 	int rtn;
 
+	/*
+	 * We need saved copies of a number of fields - this is because
+	 * error handling may need to overwrite these with different values
+	 * to run different commands, and once error handling is complete,
+	 * we will need to restore these values prior to running the actual
+	 * command.
+	 */
+	old_buffer = scmd->request_buffer;
+	old_bufflen = scmd->request_bufflen;
+	memcpy(old_cmnd, scmd->cmnd, sizeof(scmd->cmnd));
+	old_data_direction = scmd->sc_data_direction;
+	old_cmd_len = scmd->cmd_len;
+	old_use_sg = scmd->use_sg;
+
+	if (copy_sense) {
+		int gfp_mask = GFP_ATOMIC;
+
+		if (shost->hostt->unchecked_isa_dma)
+			gfp_mask |= __GFP_DMA;
+
+		scmd->sc_data_direction = DMA_FROM_DEVICE;
+		scmd->request_bufflen = 252;
+		scmd->request_buffer = kzalloc(scmd->request_bufflen, gfp_mask);
+		if (!scmd->request_buffer)
+			return FAILED;
+	} else {
+		scmd->request_buffer = NULL;
+		scmd->request_bufflen = 0;
+		scmd->sc_data_direction = DMA_NONE;
+	}
+
+	scmd->underflow = 0;
+	scmd->use_sg = 0;
+	scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
+
 	if (sdev->scsi_level <= SCSI_2)
 		scmd->cmnd[1] = (scmd->cmnd[1] & 0x1f) |
 			(sdev->lun << 5 & 0xe0);
 
+	/*
+	 * Zero the sense buffer.  The scsi spec mandates that any
+	 * untransferred sense data should be interpreted as being zero.
+	 */
+	memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
+
 	shost->eh_action = &done;
 
 	spin_lock_irqsave(shost->host_lock, flags);
@@ -522,6 +570,29 @@
 		rtn = FAILED;
 	}
 
+
+	/*
+	 * Last chance to have valid sense data.
+	 */
+	if (copy_sense) {
+		if (!SCSI_SENSE_VALID(scmd)) {
+			memcpy(scmd->sense_buffer, scmd->request_buffer,
+			       sizeof(scmd->sense_buffer));
+		}
+		kfree(scmd->request_buffer);
+	}
+
+
+	/*
+	 * Restore original data
+	 */
+	scmd->request_buffer = old_buffer;
+	scmd->request_bufflen = old_bufflen;
+	memcpy(scmd->cmnd, old_cmnd, sizeof(scmd->cmnd));
+	scmd->sc_data_direction = old_data_direction;
+	scmd->cmd_len = old_cmd_len;
+	scmd->use_sg = old_use_sg;
+	scmd->result = old_result;
 	return rtn;
 }
 
@@ -537,56 +608,10 @@
 static int scsi_request_sense(struct scsi_cmnd *scmd)
 {
 	static unsigned char generic_sense[6] =
-	{REQUEST_SENSE, 0, 0, 0, 252, 0};
-	unsigned char *scsi_result;
-	int saved_result;
-	int rtn;
+		{REQUEST_SENSE, 0, 0, 0, 252, 0};
 
 	memcpy(scmd->cmnd, generic_sense, sizeof(generic_sense));
-
-	scsi_result = kmalloc(252, GFP_ATOMIC | ((scmd->device->host->hostt->unchecked_isa_dma) ? __GFP_DMA : 0));
-
-
-	if (unlikely(!scsi_result)) {
-		printk(KERN_ERR "%s: cannot allocate scsi_result.\n",
-		       __FUNCTION__);
-		return FAILED;
-	}
-
-	/*
-	 * zero the sense buffer.  some host adapters automatically always
-	 * request sense, so it is not a good idea that
-	 * scmd->request_buffer and scmd->sense_buffer point to the same
-	 * address (db).  0 is not a valid sense code. 
-	 */
-	memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
-	memset(scsi_result, 0, 252);
-
-	saved_result = scmd->result;
-	scmd->request_buffer = scsi_result;
-	scmd->request_bufflen = 252;
-	scmd->use_sg = 0;
-	scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
-	scmd->sc_data_direction = DMA_FROM_DEVICE;
-	scmd->underflow = 0;
-
-	rtn = scsi_send_eh_cmnd(scmd, SENSE_TIMEOUT);
-
-	/* last chance to have valid sense data */
-	if(!SCSI_SENSE_VALID(scmd)) {
-		memcpy(scmd->sense_buffer, scmd->request_buffer,
-		       sizeof(scmd->sense_buffer));
-	}
-
-	kfree(scsi_result);
-
-	/*
-	 * when we eventually call scsi_finish, we really wish to complete
-	 * the original request, so let's restore the original data. (db)
-	 */
-	scsi_setup_cmd_retry(scmd);
-	scmd->result = saved_result;
-	return rtn;
+	return scsi_send_eh_cmnd(scmd, SENSE_TIMEOUT, 1);
 }
 
 /**
@@ -605,12 +630,6 @@
 {
 	scmd->device->host->host_failed--;
 	scmd->eh_eflags = 0;
-
-	/*
-	 * set this back so that the upper level can correctly free up
-	 * things.
-	 */
-	scsi_setup_cmd_retry(scmd);
 	list_move_tail(&scmd->eh_entry, done_q);
 }
 EXPORT_SYMBOL(scsi_eh_finish_cmd);
@@ -715,47 +734,26 @@
 {
 	static unsigned char tur_command[6] = {TEST_UNIT_READY, 0, 0, 0, 0, 0};
 	int retry_cnt = 1, rtn;
-	int saved_result;
 
 retry_tur:
 	memcpy(scmd->cmnd, tur_command, sizeof(tur_command));
 
-	/*
-	 * zero the sense buffer.  the scsi spec mandates that any
-	 * untransferred sense data should be interpreted as being zero.
-	 */
-	memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
-
-	saved_result = scmd->result;
-	scmd->request_buffer = NULL;
-	scmd->request_bufflen = 0;
-	scmd->use_sg = 0;
-	scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
-	scmd->underflow = 0;
-	scmd->sc_data_direction = DMA_NONE;
-
-	rtn = scsi_send_eh_cmnd(scmd, SENSE_TIMEOUT);
 
-	/*
-	 * when we eventually call scsi_finish, we really wish to complete
-	 * the original request, so let's restore the original data. (db)
-	 */
-	scsi_setup_cmd_retry(scmd);
-	scmd->result = saved_result;
+	rtn = scsi_send_eh_cmnd(scmd, SENSE_TIMEOUT, 0);
 
-	/*
-	 * hey, we are done.  let's look to see what happened.
-	 */
 	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
 		__FUNCTION__, scmd, rtn));
-	if (rtn == SUCCESS)
-		return 0;
-	else if (rtn == NEEDS_RETRY) {
+
+	switch (rtn) {
+	case NEEDS_RETRY:
 		if (retry_cnt--)
 			goto retry_tur;
+		/*FALLTHRU*/
+	case SUCCESS:
 		return 0;
+	default:
+		return 1;
 	}
-	return 1;
 }
 
 /**
@@ -837,44 +835,16 @@
 static int scsi_eh_try_stu(struct scsi_cmnd *scmd)
 {
 	static unsigned char stu_command[6] = {START_STOP, 0, 0, 0, 1, 0};
-	int rtn;
-	int saved_result;
 
-	if (!scmd->device->allow_restart)
-		return 1;
-
-	memcpy(scmd->cmnd, stu_command, sizeof(stu_command));
-
-	/*
-	 * zero the sense buffer.  the scsi spec mandates that any
-	 * untransferred sense data should be interpreted as being zero.
-	 */
-	memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
-
-	saved_result = scmd->result;
-	scmd->request_buffer = NULL;
-	scmd->request_bufflen = 0;
-	scmd->use_sg = 0;
-	scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
-	scmd->underflow = 0;
-	scmd->sc_data_direction = DMA_NONE;
+	if (scmd->device->allow_restart) {
+		int rtn;
 
-	rtn = scsi_send_eh_cmnd(scmd, START_UNIT_TIMEOUT);
-
-	/*
-	 * when we eventually call scsi_finish, we really wish to complete
-	 * the original request, so let's restore the original data. (db)
-	 */
-	scsi_setup_cmd_retry(scmd);
-	scmd->result = saved_result;
+		memcpy(scmd->cmnd, stu_command, sizeof(stu_command));
+		rtn = scsi_send_eh_cmnd(scmd, START_UNIT_TIMEOUT, 0);
+		if (rtn == SUCCESS)
+			return 0;
+	}
 
-	/*
-	 * hey, we are done.  let's look to see what happened.
-	 */
-	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
-		__FUNCTION__, scmd, rtn));
-	if (rtn == SUCCESS)
-		return 0;
 	return 1;
 }
 
@@ -1684,8 +1654,6 @@
     
 	scmd->scsi_done		= scsi_reset_provider_done_command;
 	scmd->done			= NULL;
-	scmd->buffer			= NULL;
-	scmd->bufflen			= 0;
 	scmd->request_buffer		= NULL;
 	scmd->request_bufflen		= 0;
 
drivers/scsi/scsi_lib.c +6 -82

152 lines not on this page · raw message

drivers/scsi/scsi.c +1 -10
Index: scsi-misc-2.6/drivers/scsi/scsi.c
===================================================================
@@ -346,7 +346,7 @@
 			if (level > 3) {
 				printk(KERN_INFO "buffer = 0x%p, bufflen = %d,"
 				       " done = 0x%p, queuecommand 0x%p\n",
-					cmd->buffer, cmd->bufflen,
+					cmd->request_buffer, cmd->request_bufflen,
 					cmd->done,
 					sdev->host->hostt->queuecommand);
 
@@ -661,11 +661,6 @@
  */
 int scsi_retry_command(struct scsi_cmnd *cmd)
 {
-	/*
-	 * Restore the SCSI command state.
-	 */
-	scsi_setup_cmd_retry(cmd);
-
         /*
          * Zero the sense information from the last time we tried
          * this command.
@@ -711,10 +706,6 @@
 				"Notifying upper driver of completion "
 				"(result %x)\n", cmd->result));
 
-	/*
-	 * We can get here with use_sg=0, causing a panic in the upper level
-	 */
-	cmd->use_sg = cmd->old_use_sg;
 	cmd->done(cmd);
 }
 EXPORT_SYMBOL(scsi_finish_command);
include/scsi/scsi_cmnd.h +0 -9
Index: scsi-misc-2.6/include/scsi/scsi_cmnd.h
===================================================================
@@ -58,9 +58,7 @@
 	int timeout_per_command;
 
 	unsigned char cmd_len;
-	unsigned char old_cmd_len;
 	enum dma_data_direction sc_data_direction;
-	enum dma_data_direction sc_old_data_direction;
 
 	/* These elements define the operation we are about to perform */
 #define MAX_COMMAND_SIZE	16
@@ -71,18 +69,11 @@
 	void *request_buffer;		/* Actual requested buffer */
 
 	/* These elements define the operation we ultimately want to perform */
-	unsigned char data_cmnd[MAX_COMMAND_SIZE];
-	unsigned short old_use_sg;	/* We save  use_sg here when requesting
-					 * sense info */
 	unsigned short use_sg;	/* Number of pieces of scatter-gather */
 	unsigned short sglist_len;	/* size of malloc'd scatter-gather list */
-	unsigned bufflen;	/* Size of data buffer */
-	void *buffer;		/* Data buffer */
 
 	unsigned underflow;	/* Return error if less than
 				   this amount is transferred */
-	unsigned old_underflow;	/* save underflow here when reusing the
-				 * command for error handling */
 
 	unsigned transfersize;	/* How much we are guaranteed to
 				   transfer with each SCSI transfer
drivers/scsi/scsi_priv.h +0 -1
Index: scsi-misc-2.6/drivers/scsi/scsi_priv.h
===================================================================
@@ -57,7 +57,6 @@
 
 /* scsi_lib.c */
 extern int scsi_maybe_unblock_host(struct scsi_device *sdev);
-extern void scsi_setup_cmd_retry(struct scsi_cmnd *cmd);
 extern void scsi_device_unbusy(struct scsi_device *sdev);
 extern int scsi_queue_insert(struct scsi_cmnd *cmd, int reason);
 extern void scsi_next_command(struct scsi_cmnd *cmd);
drivers/scsi/sd.c +1 -2
Index: scsi-misc-2.6/drivers/scsi/sd.c
===================================================================
@@ -502,8 +502,7 @@
 		SCpnt->cmnd[4] = (unsigned char) this_count;
 		SCpnt->cmnd[5] = 0;
 	}
-	SCpnt->request_bufflen = SCpnt->bufflen =
-			this_count * sdp->sector_size;
+	SCpnt->request_bufflen = this_count * sdp->sector_size;
 
 	/*
 	 * We shouldn't disconnect in the middle of a sector, so with a dumb
drivers/scsi/sr.c +2 -3
Index: scsi-misc-2.6/drivers/scsi/sr.c
===================================================================
@@ -360,7 +360,7 @@
 				"mismatch count %d, bytes %d\n",
 				size, SCpnt->request_bufflen);
 			if (SCpnt->request_bufflen > size)
-				SCpnt->request_bufflen = SCpnt->bufflen = size;
+				SCpnt->request_bufflen = size;
 		}
 	}
 
@@ -387,8 +387,7 @@
 
 	if (this_count > 0xffff) {
 		this_count = 0xffff;
-		SCpnt->request_bufflen = SCpnt->bufflen =
-				this_count * s_size;
+		SCpnt->request_bufflen = this_count * s_size;
 	}
 
 	SCpnt->cmnd[2] = (unsigned char) (block >> 24) & 0xff;
drivers/scsi/aha152x.c +9 -5
Index: scsi-misc-2.6/drivers/scsi/aha152x.c
===================================================================
@@ -1165,6 +1165,10 @@
 	DECLARE_MUTEX_LOCKED(sem);
 	struct timer_list timer;
 	int ret, issued, disconnected;
+	unsigned char old_cmd_len = SCpnt->cmd_len;
+	unsigned short old_use_sg = SCpnt->use_sg;
+	void *old_buffer = SCpnt->request_buffer;
+	unsigned old_bufflen = SCpnt->request_bufflen;
 	unsigned long flags;
 
 #if defined(AHA152X_DEBUG)
@@ -1198,11 +1202,11 @@
 	add_timer(&timer);
 	down(&sem);
 	del_timer(&timer);
-	
-	SCpnt->cmd_len         = SCpnt->old_cmd_len;
-	SCpnt->use_sg          = SCpnt->old_use_sg;
-  	SCpnt->request_buffer  = SCpnt->buffer;
-       	SCpnt->request_bufflen = SCpnt->bufflen;
+
+	SCpnt->cmd_len         = old_cmd_len;
+	SCpnt->use_sg          = old_use_sg;
+  	SCpnt->request_buffer  = old_buffer;
+       	SCpnt->request_bufflen = old_bufflen;
 
 	DO_LOCK(flags);