[RFC PATCH 26/32] ide-tape: remove packet command and struct request memory buffers

[Borislav Petkov <petkovbb@gmail.com>]

From: Borislav Petkov <bbpetkov@yahoo.de>

Bart,
this one is rather intrusive so please doublecheck it wrt to kzalloc/kfree
balancing on all the codepaths so that we don't leak memory all over the place.
I free all the alloc'd pc's and rq's in idetape_end_request() which is called
from the callback idetape_pc_callback() registered with the packet command
struct when creating the respective ATAPI cmd.

---
These buffers were always statically allocated during driver initialization no
matter what. Remove them by allocating GFP_ATOMIC memory on demand. In the case
of allocation error, we only issue error msg in the *alloc_{pc,rq} thus postponing
the final error handling and cleanup in their callers. Packet command and
request memory is freed in idetape_end_request() which is at the end of the
request path entered from all the callbacks.

Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de>
---
 drivers/ide/ide-tape.c |  122 ++++++++++++++++++++++-------------------------
 1 files changed, 57 insertions(+), 65 deletions(-)

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 041edcd..3c1a7db 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -105,13 +105,6 @@ enum {
 #define IDETAPE_PC_BUFFER_SIZE		256
 
 /*
- *	In various places in the driver, we need to allocate storage
- *	for packet commands and requests, which will remain valid while
- *	we leave the driver to wait for an interrupt or a timeout event.
- */
-#define IDETAPE_PC_STACK		(10 + IDETAPE_MAX_PC_RETRIES)
-
-/*
  * Some drives (for example, Seagate STT3401A Travan) require a very long
  * timeout, because they don't return an interrupt or clear their busy bit
  * until after the command completes (even retension commands).
@@ -271,13 +264,6 @@ typedef struct ide_tape_obj {
 	 */
 	idetape_pc_t *failed_pc;
 
-	idetape_pc_t pc_stack[IDETAPE_PC_STACK];
-	/* Next free packet command storage space */
-	int pc_stack_idx;
-	struct request rq_stack[IDETAPE_PC_STACK];
-	/* We implement a circular array */
-	int rq_stack_idx;
-
 	/*
 	 * DSC polling variables.
 	 *
@@ -669,45 +655,32 @@ static void idetape_update_buffers (idetape_pc_t *pc)
 	pc->bh = bh;
 }
 
-/*
- *	idetape_next_pc_storage returns a pointer to a place in which we can
- *	safely store a packet command, even though we intend to leave the
- *	driver. A storage space for a maximum of IDETAPE_PC_STACK packet
- *	commands is allocated at initialization time.
- */
-static idetape_pc_t *idetape_next_pc_storage (ide_drive_t *drive)
+static idetape_pc_t *ide_tape_alloc_pc(void)
 {
-	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t *pc;
 
-	debug_log(DBG_PCRQ_STACK, "pc_stack_index=%d\n", tape->pc_stack_idx);
+	pc = kzalloc(sizeof(idetape_pc_t), GFP_ATOMIC);
+	if (!pc)
+		printk(KERN_ERR "ide-tape: %s: memory allocation error.",
+				__func__);
 
-	if (tape->pc_stack_idx == IDETAPE_PC_STACK)
-		tape->pc_stack_idx = 0;
-	return (&tape->pc_stack[tape->pc_stack_idx++]);
+	return pc;
 }
 
 /*
- *	idetape_next_rq_storage is used along with idetape_next_pc_storage.
- *	Since we queue packet commands in the request queue, we need to
- *	allocate a request, along with the allocation of a packet command.
+ * Since we queue packet commands in the request queue, we need to allocate a
+ * request, along with a packet command.
  */
- 
-/**************************************************************
- *                                                            *
- *  This should get fixed to use kmalloc(.., GFP_ATOMIC)      *
- *  followed later on by kfree().   -ml                       *
- *                                                            *
- **************************************************************/
- 
-static struct request *idetape_next_rq_storage (ide_drive_t *drive)
+static struct request *ide_tape_alloc_rq(void)
 {
-	idetape_tape_t *tape = drive->driver_data;
+	struct request *rq;
 
-	debug_log(DBG_PCRQ_STACK, "rq_stack_index=%d\n", tape->rq_stack_idx);
+	rq = kzalloc(sizeof(struct request), GFP_ATOMIC);
+	if (!rq)
+		printk(KERN_ERR "ide-tape: %s: memory allocation error.",
+				__func__);
 
-	if (tape->rq_stack_idx == IDETAPE_PC_STACK)
-		tape->rq_stack_idx = 0;
-	return (&tape->rq_stack[tape->rq_stack_idx++]);
+	return rq;
 }
 
 /*
@@ -981,9 +954,8 @@ static int idetape_end_request(ide_drive_t *drive, int uptodate, int nr_sects)
 		}
 	}
 	ide_end_drive_cmd(drive, 0, 0);
-//	blkdev_dequeue_request(rq);
-//	drive->rq = NULL;
-//	end_that_request_last(rq);
+	kfree(tape->pc);
+	kfree(rq);
 
 	if (remove_stage)
 		idetape_remove_stage_head(drive);
@@ -1032,13 +1004,9 @@ static void idetape_init_rq(struct request *rq, u8 cmd)
  *
  *	idetape_queue_pc_head is called from the request handling part of
  *	the driver (the "bottom" part). Safe storage for the request should
- *	be allocated with idetape_next_pc_storage and idetape_next_rq_storage
+ *	be allocated with ide_tape_alloc_pc and ide_tape_alloc_rq
  *	before calling idetape_queue_pc_head.
  *
- *	Memory for those requests is pre-allocated at initialization time, and
- *	is limited to IDETAPE_PC_STACK requests. We assume that we have enough
- *	space for the maximum possible number of inter-dependent packet commands.
- *
  *	The higher level of the driver - The ioctl handler and the character
  *	device handling functions should queue request to the lower level part
  *	and wait for their completion using idetape_queue_pc_tail or
@@ -1055,19 +1023,27 @@ static void idetape_queue_pc_head (ide_drive_t *drive, idetape_pc_t *pc,struct r
 }
 
 /*
- *	idetape_retry_pc is called when an error was detected during the
- *	last packet command. We queue a request sense packet command in
- *	the head of the request list.
+ * Called when an error was detected during the last packet command. We queue a
+ * request sense packet command in the head of the request list.
  */
-static ide_startstop_t idetape_retry_pc (ide_drive_t *drive)
+static ide_startstop_t idetape_retry_pc(ide_drive_t *drive)
 {
 	idetape_tape_t *tape = drive->driver_data;
 	idetape_pc_t *pc;
 	struct request *rq;
 
 	(void)drive->hwif->INB(IDE_ERROR_REG);
-	pc = idetape_next_pc_storage(drive);
-	rq = idetape_next_rq_storage(drive);
+	pc = ide_tape_alloc_pc();
+	rq = ide_tape_alloc_rq();
+
+	if (!pc || !rq) {
+		printk(KERN_ERR "ide-tape: Cannot retry packet command due to "
+				"low memory.");
+		kfree(pc);
+		kfree(rq);
+		return ide_stopped;
+	}
+
 	idetape_create_request_sense_cmd(pc);
 	set_bit(IDETAPE_IGNORE_DSC, &tape->flags);
 	idetape_queue_pc_head(drive, pc, rq);
@@ -1719,21 +1695,33 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
 	if (rq->cmd[0] & REQ_IDETAPE_READ) {
 		tape->buffer_head++;
 		tape->postpone_cnt = 0;
-		pc = idetape_next_pc_storage(drive);
-		idetape_create_read_cmd(tape, pc, rq->current_nr_sectors, (struct idetape_bh *)rq->special);
+		pc = ide_tape_alloc_pc();
+		if (!pc)
+			goto err;
+
+		idetape_create_read_cmd(tape, pc, rq->current_nr_sectors,
+				(struct idetape_bh *)rq->special);
 		goto out;
 	}
 	if (rq->cmd[0] & REQ_IDETAPE_WRITE) {
 		tape->buffer_head++;
 		tape->postpone_cnt = 0;
-		pc = idetape_next_pc_storage(drive);
-		idetape_create_write_cmd(tape, pc, rq->current_nr_sectors, (struct idetape_bh *)rq->special);
+		pc = ide_tape_alloc_pc();
+		if (!pc)
+			goto err;
+
+		idetape_create_write_cmd(tape, pc, rq->current_nr_sectors,
+				(struct idetape_bh *)rq->special);
 		goto out;
 	}
 	if (rq->cmd[0] & REQ_IDETAPE_READ_BUFFER) {
 		tape->postpone_cnt = 0;
-		pc = idetape_next_pc_storage(drive);
-		idetape_create_read_buffer_cmd(tape, pc, rq->current_nr_sectors, (struct idetape_bh *)rq->special);
+		pc = ide_tape_alloc_pc();
+		if (!pc)
+			goto err;
+
+		idetape_create_read_buffer_cmd(tape, pc, rq->current_nr_sectors,
+				(struct idetape_bh *)rq->special);
 		goto out;
 	}
 	if (rq->cmd[0] & REQ_IDETAPE_PC1) {
@@ -1749,6 +1737,11 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
 	BUG();
 out:
 	return idetape_issue_packet_command(drive, pc);
+
+err:
+	printk(KERN_ERR "ide-tape: Error processing request %u\n", rq->cmd[0]);
+	idetape_end_request(drive, 0, 0);
+	return ide_stopped;
 }
 
 /*
@@ -2055,7 +2048,7 @@ static void idetape_create_test_unit_ready_cmd(idetape_pc_t *pc)
  *	for an interrupt or a timer event.
  *
  *	From the bottom part of the driver, we should allocate safe memory
- *	using idetape_next_pc_storage and idetape_next_rq_storage, and add
+ *	using ide_tape_alloc_pc and ide_tape_alloc_rq, and add
  *	the request to the request list without waiting for it to be serviced !
  *	In that case, we usually use idetape_queue_pc_head.
  */
@@ -3644,7 +3637,6 @@ static void idetape_setup (ide_drive_t *drive, idetape_tape_t *tape, int minor)
 	tape->name[1] = 't';
 	tape->name[2] = '0' + minor;
 	tape->chrdev_dir = idetape_dir_none;
-	tape->pc = tape->pc_stack;
 	tape->max_ins_speed = 10000;
 	tape->speed_ctl = 1;
 	*((unsigned short *) &gcw) = drive->id->config;
-- 
1.5.3.7