[PATCH 0/3] ide-tape: misc stuff

[PATCH 0/3] ide-tape: misc stuff

[Borislav Petkov]

Hi David,

here's a re-spun version with patch 2 dropped.

* 0001: somehow fell through the cracks, DEBUG build fix

* 0002: this one converts ide-tape to the debugging scheme we use with ide-cd
  and ide-floppy. It adds some debug calls at important places and has proven
  very helpful when working on bug reports with users. No functional change.

* 0003: real bugfix

The patches are also at

	git://git.kernel.org/pub/scm/linux/kernel/git/bp/bp.git ide-tape-postponed


--
Thanks,
Boris.

[PATCH 1/3] ide-tape: fix debug call

[Borislav Petkov]

From: Mark de Wever <koraq@xs4all.nl>

This error only occurs when IDETAPE_DEBUG_LOG is enabled.

Signed-off-by: Mark de Wever <koraq@xs4all.nl>
---
 drivers/ide/ide-tape.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 013dc59..60d5c41 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -583,7 +583,7 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
 	struct ide_cmd cmd;
 	u8 stat;
 
-	debug_log(DBG_SENSE, "sector: %llu, nr_sectors: %u\n"
+	debug_log(DBG_SENSE, "sector: %llu, nr_sectors: %u\n",
 		  (unsigned long long)blk_rq_pos(rq), blk_rq_sectors(rq));
 
 	BUG_ON(!(blk_special_request(rq) || blk_sense_request(rq)));
-- 
1.6.3.3

[PATCH 2/3] ide-tape: convert to ide_debug_log macro

[Borislav Petkov]

Remove tape->debug_mask and use drive->debug_mask instead.

There should be no functional change resulting from this patch.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
---
 drivers/ide/ide-tape.c |  102 +++++++++++++++++++++++-------------------------
 1 files changed, 49 insertions(+), 53 deletions(-)

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 60d5c41..08f09f5 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -47,28 +47,13 @@
 #include <asm/unaligned.h>
 #include <linux/mtio.h>
 
-enum {
-	/* output errors only */
-	DBG_ERR =		(1 << 0),
-	/* output all sense key/asc */
-	DBG_SENSE =		(1 << 1),
-	/* info regarding all chrdev-related procedures */
-	DBG_CHRDEV =		(1 << 2),
-	/* all remaining procedures */
-	DBG_PROCS =		(1 << 3),
-};
-
 /* define to see debug info */
-#define IDETAPE_DEBUG_LOG		0
+#undef IDETAPE_DEBUG_LOG
 
-#if IDETAPE_DEBUG_LOG
-#define debug_log(lvl, fmt, args...)			\
-{							\
-	if (tape->debug_mask & lvl)			\
-	printk(KERN_INFO "ide-tape: " fmt, ## args);	\
-}
+#ifdef IDETAPE_DEBUG_LOG
+#define ide_debug_log(lvl, fmt, args...) __ide_debug_log(lvl, fmt, ## args)
 #else
-#define debug_log(lvl, fmt, args...) do {} while (0)
+#define ide_debug_log(lvl, fmt, args...) do {} while (0)
 #endif
 
 /**************************** Tunable parameters *****************************/
@@ -230,8 +215,6 @@ typedef struct ide_tape_obj {
 	char drv_write_prot;
 	/* the tape is write protected (hardware or opened as read-only) */
 	char write_prot;
-
-	u32 debug_mask;
 } idetape_tape_t;
 
 static DEFINE_MUTEX(idetape_ref_mutex);
@@ -290,8 +273,9 @@ static void idetape_analyze_error(ide_drive_t *drive)
 	tape->asc       = sense[12];
 	tape->ascq      = sense[13];
 
-	debug_log(DBG_ERR, "pc = %x, sense key = %x, asc = %x, ascq = %x\n",
-		 pc->c[0], tape->sense_key, tape->asc, tape->ascq);
+	ide_debug_log(IDE_DBG_FUNC,
+		      "cmd: 0x%x, sense key = %x, asc = %x, ascq = %x",
+		      rq->cmd[0], tape->sense_key, tape->asc, tape->ascq);
 
 	/* correct remaining bytes to transfer */
 	if (pc->flags & PC_FLAG_DMA_ERROR)
@@ -344,7 +328,8 @@ static int ide_tape_callback(ide_drive_t *drive, int dsc)
 	int uptodate = pc->error ? 0 : 1;
 	int err = uptodate ? 0 : IDE_DRV_ERROR_GENERAL;
 
-	debug_log(DBG_PROCS, "Enter %s\n", __func__);
+	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x, dsc: %d, err: %d", rq->cmd[0],
+		      dsc, err);
 
 	if (dsc)
 		ide_tape_handle_dsc(drive);
@@ -390,10 +375,12 @@ static int ide_tape_callback(ide_drive_t *drive, int dsc)
 static void idetape_postpone_request(ide_drive_t *drive)
 {
 	idetape_tape_t *tape = drive->driver_data;
+	struct request *rq = drive->hwif->rq;
 
-	debug_log(DBG_PROCS, "Enter %s\n", __func__);
+	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x, dsc_poll_freq: %lu",
+		      rq->cmd[0], tape->dsc_poll_freq);
 
-	tape->postponed_rq = drive->hwif->rq;
+	tape->postponed_rq = rq;
 
 	ide_stall_queue(drive, tape->dsc_poll_freq);
 }
@@ -488,7 +475,8 @@ static ide_startstop_t ide_tape_issue_pc(ide_drive_t *drive,
 		ide_complete_rq(drive, -EIO, blk_rq_bytes(rq));
 		return ide_stopped;
 	}
-	debug_log(DBG_SENSE, "Retry #%d, cmd = %02X\n", pc->retries, pc->c[0]);
+	ide_debug_log(IDE_DBG_SENSE, "retry #%d, cmd: 0x%02x", pc->retries,
+		      pc->c[0]);
 
 	pc->retries++;
 
@@ -583,8 +571,9 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
 	struct ide_cmd cmd;
 	u8 stat;
 
-	debug_log(DBG_SENSE, "sector: %llu, nr_sectors: %u\n",
-		  (unsigned long long)blk_rq_pos(rq), blk_rq_sectors(rq));
+	ide_debug_log(IDE_DBG_RQ, "cmd: 0x%x, sector: %llu, nr_sectors: %u",
+		      rq->cmd[0], (unsigned long long)blk_rq_pos(rq),
+		      blk_rq_sectors(rq));
 
 	BUG_ON(!(blk_special_request(rq) || blk_sense_request(rq)));
 
@@ -745,7 +734,7 @@ static int ide_tape_read_position(ide_drive_t *drive)
 	struct ide_atapi_pc pc;
 	u8 buf[20];
 
-	debug_log(DBG_PROCS, "Enter %s\n", __func__);
+	ide_debug_log(IDE_DBG_FUNC, "enter");
 
 	/* prep cmd */
 	ide_init_pc(&pc);
@@ -756,9 +745,9 @@ static int ide_tape_read_position(ide_drive_t *drive)
 		return -1;
 
 	if (!pc.error) {
-		debug_log(DBG_SENSE, "BOP - %s\n",
+		ide_debug_log(IDE_DBG_FUNC, "BOP - %s",
 				(buf[0] & 0x80) ? "Yes" : "No");
-		debug_log(DBG_SENSE, "EOP - %s\n",
+		ide_debug_log(IDE_DBG_FUNC, "EOP - %s",
 				(buf[0] & 0x40) ? "Yes" : "No");
 
 		if (buf[0] & 0x4) {
@@ -768,8 +757,8 @@ static int ide_tape_read_position(ide_drive_t *drive)
 				  &drive->atapi_flags);
 			return -1;
 		} else {
-			debug_log(DBG_SENSE, "Block Location - %u\n",
-					be32_to_cpup((__be32 *)&buf[4]));
+			ide_debug_log(IDE_DBG_FUNC, "Block Location: %u",
+				      be32_to_cpup((__be32 *)&buf[4]));
 
 			tape->partition = buf[1];
 			tape->first_frame = be32_to_cpup((__be32 *)&buf[4]);
@@ -866,7 +855,8 @@ static int idetape_queue_rw_tail(ide_drive_t *drive, int cmd, int size)
 	struct request *rq;
 	int ret;
 
-	debug_log(DBG_SENSE, "%s: cmd=%d\n", __func__, cmd);
+	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x, size: %d", cmd, size);
+
 	BUG_ON(cmd != REQ_IDETAPE_READ && cmd != REQ_IDETAPE_WRITE);
 	BUG_ON(size < 0 || size % tape->blk_size);
 
@@ -1029,7 +1019,7 @@ static int idetape_rewind_tape(ide_drive_t *drive)
 	struct ide_atapi_pc pc;
 	int ret;
 
-	debug_log(DBG_SENSE, "Enter %s\n", __func__);
+	ide_debug_log(IDE_DBG_FUNC, "enter");
 
 	idetape_create_rewind_cmd(drive, &pc);
 	ret = ide_queue_pc_tail(drive, disk, &pc, NULL, 0);
@@ -1055,7 +1045,7 @@ static int idetape_blkdev_ioctl(ide_drive_t *drive, unsigned int cmd,
 		int nr_stages;
 	} config;
 
-	debug_log(DBG_PROCS, "Enter %s\n", __func__);
+	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%04x", cmd);
 
 	switch (cmd) {
 	case 0x0340:
@@ -1084,6 +1074,9 @@ static int idetape_space_over_filemarks(ide_drive_t *drive, short mt_op,
 	int retval, count = 0;
 	int sprev = !!(tape->caps[4] & 0x20);
 
+
+	ide_debug_log(IDE_DBG_FUNC, "mt_op: %d, mt_count: %d", mt_op, mt_count);
+
 	if (mt_count == 0)
 		return 0;
 	if (MTBSF == mt_op || MTBSFM == mt_op) {
@@ -1147,7 +1140,7 @@ static ssize_t idetape_chrdev_read(struct file *file, char __user *buf,
 	ssize_t ret = 0;
 	int rc;
 
-	debug_log(DBG_CHRDEV, "Enter %s, count %Zd\n", __func__, count);
+	ide_debug_log(IDE_DBG_FUNC, "count %Zd", count);
 
 	if (tape->chrdev_dir != IDETAPE_DIR_READ) {
 		if (test_bit(ilog2(IDE_AFLAG_DETECT_BS), &drive->atapi_flags))
@@ -1186,8 +1179,6 @@ static ssize_t idetape_chrdev_read(struct file *file, char __user *buf,
 	}
 
 	if (!done && test_bit(ilog2(IDE_AFLAG_FILEMARK), &drive->atapi_flags)) {
-		debug_log(DBG_SENSE, "%s: spacing over filemark\n", tape->name);
-
 		idetape_space_over_filemarks(drive, MTFSF, 1);
 		return 0;
 	}
@@ -1208,7 +1199,7 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
 	if (tape->write_prot)
 		return -EACCES;
 
-	debug_log(DBG_CHRDEV, "Enter %s, count %Zd\n", __func__, count);
+	ide_debug_log(IDE_DBG_FUNC, "count %Zd", count);
 
 	/* Initialize write operation */
 	rc = idetape_init_rw(drive, IDETAPE_DIR_WRITE);
@@ -1272,8 +1263,8 @@ static int idetape_mtioctop(ide_drive_t *drive, short mt_op, int mt_count)
 	struct ide_atapi_pc pc;
 	int i, retval;
 
-	debug_log(DBG_ERR, "Handling MTIOCTOP ioctl: mt_op=%d, mt_count=%d\n",
-			mt_op, mt_count);
+	ide_debug_log(IDE_DBG_FUNC, "MTIOCTOP ioctl: mt_op: %d, mt_count: %d",
+		      mt_op, mt_count);
 
 	switch (mt_op) {
 	case MTFSF:
@@ -1392,7 +1383,7 @@ static int idetape_chrdev_ioctl(struct inode *inode, struct file *file,
 	int block_offset = 0, position = tape->first_frame;
 	void __user *argp = (void __user *)arg;
 
-	debug_log(DBG_CHRDEV, "Enter %s, cmd=%u\n", __func__, cmd);
+	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x", cmd);
 
 	if (tape->chrdev_dir == IDETAPE_DIR_WRITE) {
 		ide_tape_flush_merge_buffer(drive);
@@ -1460,6 +1451,9 @@ static void ide_tape_get_bsize_from_bdesc(ide_drive_t *drive)
 				(buf[4 + 6] << 8)  +
 				 buf[4 + 7];
 	tape->drv_write_prot = (buf[2] & 0x80) >> 7;
+
+	ide_debug_log(IDE_DBG_FUNC, "blk_size: %d, write_prot: %d",
+		      tape->blk_size, tape->drv_write_prot);
 }
 
 static int idetape_chrdev_open(struct inode *inode, struct file *filp)
@@ -1479,7 +1473,10 @@ static int idetape_chrdev_open(struct inode *inode, struct file *filp)
 		return -ENXIO;
 	}
 
-	debug_log(DBG_CHRDEV, "Enter %s\n", __func__);
+	drive = tape->drive;
+	filp->private_data = tape;
+
+	ide_debug_log(IDE_DBG_FUNC, "enter");
 
 	/*
 	 * We really want to do nonseekable_open(inode, filp); here, but some
@@ -1488,9 +1485,6 @@ static int idetape_chrdev_open(struct inode *inode, struct file *filp)
 	 */
 	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
 
-	drive = tape->drive;
-
-	filp->private_data = tape;
 
 	if (test_and_set_bit(ilog2(IDE_AFLAG_BUSY), &drive->atapi_flags)) {
 		retval = -EBUSY;
@@ -1569,7 +1563,7 @@ static int idetape_chrdev_release(struct inode *inode, struct file *filp)
 	lock_kernel();
 	tape = drive->driver_data;
 
-	debug_log(DBG_CHRDEV, "Enter %s\n", __func__);
+	ide_debug_log(IDE_DBG_FUNC, "enter");
 
 	if (tape->chrdev_dir == IDETAPE_DIR_WRITE)
 		idetape_write_release(drive, minor);
@@ -1706,7 +1700,6 @@ static int divf_buffer_size(ide_drive_t *drive)	{ return 1024; }
 
 ide_devset_rw_flag(dsc_overlap, IDE_DFLAG_DSC_OVERLAP);
 
-ide_tape_devset_rw_field(debug_mask, debug_mask);
 ide_tape_devset_rw_field(tdsc, best_dsc_rw_freq);
 
 ide_tape_devset_r_field(avg_speed, avg_speed);
@@ -1718,7 +1711,6 @@ static const struct ide_proc_devset idetape_settings[] = {
 	__IDE_PROC_DEVSET(avg_speed,	0, 0xffff, NULL, NULL),
 	__IDE_PROC_DEVSET(buffer,	0, 0xffff, NULL, divf_buffer),
 	__IDE_PROC_DEVSET(buffer_size,	0, 0xffff, NULL, divf_buffer_size),
-	__IDE_PROC_DEVSET(debug_mask,	0, 0xffff, NULL, NULL),
 	__IDE_PROC_DEVSET(dsc_overlap,	0,      1, NULL, NULL),
 	__IDE_PROC_DEVSET(speed,	0, 0xffff, NULL, NULL),
 	__IDE_PROC_DEVSET(tdsc,		IDETAPE_DSC_RW_MIN, IDETAPE_DSC_RW_MAX,
@@ -1745,7 +1737,9 @@ static void idetape_setup(ide_drive_t *drive, idetape_tape_t *tape, int minor)
 	int buffer_size;
 	u16 *ctl = (u16 *)&tape->caps[12];
 
-	drive->pc_callback	 = ide_tape_callback;
+	ide_debug_log(IDE_DBG_FUNC, "minor: %d", minor);
+
+	drive->pc_callback = ide_tape_callback;
 
 	drive->dev_flags |= IDE_DFLAG_DSC_OVERLAP;
 
@@ -1931,7 +1925,9 @@ static int ide_tape_probe(ide_drive_t *drive)
 	struct gendisk *g;
 	int minor;
 
-	if (!strstr("ide-tape", drive->driver_req))
+	ide_debug_log(IDE_DBG_FUNC, "enter");
+
+	if (!strstr(DRV_NAME, drive->driver_req))
 		goto failed;
 
 	if (drive->media != ide_tape)
-- 
1.6.3.3

[PATCH 3/3] ide-tape: fix handling of postponed rqs

[Borislav Petkov]

ide-tape used to hit

[   58.614854] ide-tape: ht0: BUG: Two DSC requests queued!

due to the fact that another rq was being issued while the driver was
waiting for DSC to get set for the device executing ATAPI commands which
set the DSC to 1 to indicate completion.

Here's a sample output of that case:

issue REZERO_UNIT

[  143.088505] ide-tape: ide_tape_issue_pc: retry #0, cmd: 0x01
[  143.095122] ide: Enter ide_pc_intr - interrupt handler
[  143.096118] ide: Packet command completed, 0 bytes transferred
[  143.106319] ide-tape: ide_tape_callback: cmd: 0x1, dsc: 1, err: 0
[  143.112601] ide-tape: idetape_postpone_request: cmd: 0x1, dsc_poll_freq: 2000

we stall the ide-tape queue here waiting for DSC

[  143.119936] ide-tape: ide_tape_read_position: enter
[  145.119019] ide-tape: idetape_do_request: sector: 4294967295, nr_sectors: 0

and issue the new READ_POSITION rq and hit the check.

[  145.126247] ide-tape: ht0: BUG: Two DSC requests queued!
[  145.131748] ide-tape: ide_tape_read_position: BOP - No
[  145.137059] ide-tape: ide_tape_read_position: EOP - No

Also, ->postponed_rq used to point to that postponed request. To make
things worse, in certain circumstances the rq it was pointing to got
replaced unterneath it by swiftly reusing the same rq from the mempool
of the block layer practically confusing stuff even more.

However, we don't need to keep a pointer to that rq but simply wait for
DSC to be set first before issuing the follow-up request in the drive's
queue. In order to do that, we make idetape_do_request() first check the
DSC and if not set, we stall the drive queue giving the other device on
that IDE channel a chance.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
---
 drivers/ide/ide-tape.c |   30 ++++++++++--------------------
 1 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 08f09f5..d17074e 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -155,7 +155,8 @@ typedef struct ide_tape_obj {
 	 * other device. Note that at most we will have only one DSC (usually
 	 * data transfer) request in the device request queue.
 	 */
-	struct request *postponed_rq;
+	bool postponed_rq;
+
 	/* The time in which we started polling for DSC */
 	unsigned long dsc_polling_start;
 	/* Timer used to poll for dsc */
@@ -372,7 +373,7 @@ static int ide_tape_callback(ide_drive_t *drive, int dsc)
  * Postpone the current request so that ide.c will be able to service requests
  * from another device on the same port while we are polling for DSC.
  */
-static void idetape_postpone_request(ide_drive_t *drive)
+static void ide_tape_stall_queue(ide_drive_t *drive)
 {
 	idetape_tape_t *tape = drive->driver_data;
 	struct request *rq = drive->hwif->rq;
@@ -380,7 +381,7 @@ static void idetape_postpone_request(ide_drive_t *drive)
 	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x, dsc_poll_freq: %lu",
 		      rq->cmd[0], tape->dsc_poll_freq);
 
-	tape->postponed_rq = rq;
+	tape->postponed_rq = true;
 
 	ide_stall_queue(drive, tape->dsc_poll_freq);
 }
@@ -394,7 +395,7 @@ static void ide_tape_handle_dsc(ide_drive_t *drive)
 	tape->dsc_poll_freq = IDETAPE_DSC_MA_FAST;
 	tape->dsc_timeout = jiffies + IDETAPE_DSC_MA_TIMEOUT;
 	/* Allow ide.c to handle other requests */
-	idetape_postpone_request(drive);
+	ide_tape_stall_queue(drive);
 }
 
 /*
@@ -567,7 +568,6 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
 	ide_hwif_t *hwif = drive->hwif;
 	idetape_tape_t *tape = drive->driver_data;
 	struct ide_atapi_pc *pc = NULL;
-	struct request *postponed_rq = tape->postponed_rq;
 	struct ide_cmd cmd;
 	u8 stat;
 
@@ -583,18 +583,6 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
 		goto out;
 	}
 
-	if (postponed_rq != NULL)
-		if (rq != postponed_rq) {
-			printk(KERN_ERR "ide-tape: ide-tape.c bug - "
-					"Two DSC requests were queued\n");
-			drive->failed_pc = NULL;
-			rq->errors = 0;
-			ide_complete_rq(drive, 0, blk_rq_bytes(rq));
-			return ide_stopped;
-		}
-
-	tape->postponed_rq = NULL;
-
 	/*
 	 * If the tape is still busy, postpone our request and service
 	 * the other device meanwhile.
@@ -612,7 +600,7 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
 
 	if (!(drive->atapi_flags & IDE_AFLAG_IGNORE_DSC) &&
 	    !(stat & ATA_DSC)) {
-		if (postponed_rq == NULL) {
+		if (!tape->postponed_rq) {
 			tape->dsc_polling_start = jiffies;
 			tape->dsc_poll_freq = tape->best_dsc_rw_freq;
 			tape->dsc_timeout = jiffies + IDETAPE_DSC_RW_TIMEOUT;
@@ -629,10 +617,12 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
 					tape->dsc_polling_start +
 					IDETAPE_DSC_MA_THRESHOLD))
 			tape->dsc_poll_freq = IDETAPE_DSC_MA_SLOW;
-		idetape_postpone_request(drive);
+		ide_tape_stall_queue(drive);
 		return ide_stopped;
-	} else
+	} else {
 		drive->atapi_flags &= ~IDE_AFLAG_IGNORE_DSC;
+		tape->postponed_rq = false;
+	}
 
 	if (rq->cmd[13] & REQ_IDETAPE_READ) {
 		pc = &tape->queued_pc;
-- 
1.6.3.3

Test only.

[Sébastien Major]

Hi,

Thanks for all job : go on !

Message test only ... Trouble with Internet Mail Provider (free.fr).

See ya.
Best regards.


      

Re : Test only. [resolved]

[Sébastien Major]

Re-Hi,
Sorry to disturb : trouble resolved.

regards



----- Message d'origine ----
De : Sébastien Major <willy_the_cat@yahoo.com>
À : linux-ide@vger.kernel.org
Envoyé le : Samedi, 18 Juillet 2009, 12h24mn 36s
Objet : Test only.


Hi,

Thanks for all job : go on !

Message test only ... Trouble with Internet Mail Provider (free.fr).

See ya.
Best regards.


      
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Re: [PATCH 1/3] ide-tape: fix debug call

[David Miller]

From: Borislav Petkov <petkovbb@googlemail.com>
Date: Sat, 18 Jul 2009 11:55:15 +0200

> From: Mark de Wever <koraq@xs4all.nl>
> 
> This error only occurs when IDETAPE_DEBUG_LOG is enabled.
> 
> Signed-off-by: Mark de Wever <koraq@xs4all.nl>

Applied.

Re: [PATCH 2/3] ide-tape: convert to ide_debug_log macro

[David Miller]

From: Borislav Petkov <petkovbb@googlemail.com>
Date: Sat, 18 Jul 2009 11:55:16 +0200

> Remove tape->debug_mask and use drive->debug_mask instead.
> 
> There should be no functional change resulting from this patch.
> 
> Signed-off-by: Borislav Petkov <petkovbb@gmail.com>

Applied.

Re: [PATCH 3/3] ide-tape: fix handling of postponed rqs

[David Miller]

From: Borislav Petkov <petkovbb@googlemail.com>
Date: Sat, 18 Jul 2009 11:55:17 +0200

> ide-tape used to hit
> 
> [   58.614854] ide-tape: ht0: BUG: Two DSC requests queued!
> 
> due to the fact that another rq was being issued while the driver was
> waiting for DSC to get set for the device executing ATAPI commands which
> set the DSC to 1 to indicate completion.
> 
> Here's a sample output of that case:

Do you even compile the code you send me and look to see if there are
any new warnings generated or anything like that?

drivers/ide/ide-tape.c: In function ‘ide_tape_stall_queue’:
drivers/ide/ide-tape.c:379: warning: unused variable ‘rq’

Fix this.

Re: [PATCH 3/3] ide-tape: fix handling of postponed rqs

[Borislav Petkov]

On Tue, Jul 21, 2009 at 08:47:04PM -0700, David Miller wrote:

> drivers/ide/ide-tape.c: In function ‘ide_tape_stall_queue’:
> drivers/ide/ide-tape.c:379: warning: unused variable ‘rq’

Sorry about that, rq is used only in the debug statement and I forgot to
do a non-debug build, my bad.

--
From: Borislav Petkov <petkovbb@gmail.com>
Date: Wed, 22 Jul 2009 07:38:29 +0200
Subject: [PATCH 3/3] ide-tape: fix handling of postponed rqs

ide-tape used to hit

[   58.614854] ide-tape: ht0: BUG: Two DSC requests queued!

due to the fact that another rq was being issued while the driver was
waiting for DSC to get set for the device executing ATAPI commands which
set the DSC to 1 to indicate completion.

Here's a sample output of that case:

issue REZERO_UNIT

[  143.088505] ide-tape: ide_tape_issue_pc: retry #0, cmd: 0x01
[  143.095122] ide: Enter ide_pc_intr - interrupt handler
[  143.096118] ide: Packet command completed, 0 bytes transferred
[  143.106319] ide-tape: ide_tape_callback: cmd: 0x1, dsc: 1, err: 0
[  143.112601] ide-tape: idetape_postpone_request: cmd: 0x1, dsc_poll_freq: 2000

we stall the ide-tape queue here waiting for DSC

[  143.119936] ide-tape: ide_tape_read_position: enter
[  145.119019] ide-tape: idetape_do_request: sector: 4294967295, nr_sectors: 0

and issue the new READ_POSITION rq and hit the check.

[  145.126247] ide-tape: ht0: BUG: Two DSC requests queued!
[  145.131748] ide-tape: ide_tape_read_position: BOP - No
[  145.137059] ide-tape: ide_tape_read_position: EOP - No

Also, ->postponed_rq used to point to that postponed request. To make
things worse, in certain circumstances the rq it was pointing to got
replaced unterneath it by swiftly reusing the same rq from the mempool
of the block layer practically confusing stuff even more.

However, we don't need to keep a pointer to that rq but simply wait for
DSC to be set first before issuing the follow-up request in the drive's
queue. In order to do that, we make idetape_do_request() first check the
DSC and if not set, we stall the drive queue giving the other device on
that IDE channel a chance.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
---
 drivers/ide/ide-tape.c |   33 +++++++++++----------------------
 1 files changed, 11 insertions(+), 22 deletions(-)

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 08f09f5..96c93b0 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -155,7 +155,8 @@ typedef struct ide_tape_obj {
 	 * other device. Note that at most we will have only one DSC (usually
 	 * data transfer) request in the device request queue.
 	 */
-	struct request *postponed_rq;
+	bool postponed_rq;
+
 	/* The time in which we started polling for DSC */
 	unsigned long dsc_polling_start;
 	/* Timer used to poll for dsc */
@@ -372,15 +373,14 @@ static int ide_tape_callback(ide_drive_t *drive, int dsc)
  * Postpone the current request so that ide.c will be able to service requests
  * from another device on the same port while we are polling for DSC.
  */
-static void idetape_postpone_request(ide_drive_t *drive)
+static void ide_tape_stall_queue(ide_drive_t *drive)
 {
 	idetape_tape_t *tape = drive->driver_data;
-	struct request *rq = drive->hwif->rq;
 
 	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x, dsc_poll_freq: %lu",
-		      rq->cmd[0], tape->dsc_poll_freq);
+		      drive->hwif->rq->cmd[0], tape->dsc_poll_freq);
 
-	tape->postponed_rq = rq;
+	tape->postponed_rq = true;
 
 	ide_stall_queue(drive, tape->dsc_poll_freq);
 }
@@ -394,7 +394,7 @@ static void ide_tape_handle_dsc(ide_drive_t *drive)
 	tape->dsc_poll_freq = IDETAPE_DSC_MA_FAST;
 	tape->dsc_timeout = jiffies + IDETAPE_DSC_MA_TIMEOUT;
 	/* Allow ide.c to handle other requests */
-	idetape_postpone_request(drive);
+	ide_tape_stall_queue(drive);
 }
 
 /*
@@ -567,7 +567,6 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
 	ide_hwif_t *hwif = drive->hwif;
 	idetape_tape_t *tape = drive->driver_data;
 	struct ide_atapi_pc *pc = NULL;
-	struct request *postponed_rq = tape->postponed_rq;
 	struct ide_cmd cmd;
 	u8 stat;
 
@@ -583,18 +582,6 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
 		goto out;
 	}
 
-	if (postponed_rq != NULL)
-		if (rq != postponed_rq) {
-			printk(KERN_ERR "ide-tape: ide-tape.c bug - "
-					"Two DSC requests were queued\n");
-			drive->failed_pc = NULL;
-			rq->errors = 0;
-			ide_complete_rq(drive, 0, blk_rq_bytes(rq));
-			return ide_stopped;
-		}
-
-	tape->postponed_rq = NULL;
-
 	/*
 	 * If the tape is still busy, postpone our request and service
 	 * the other device meanwhile.
@@ -612,7 +599,7 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
 
 	if (!(drive->atapi_flags & IDE_AFLAG_IGNORE_DSC) &&
 	    !(stat & ATA_DSC)) {
-		if (postponed_rq == NULL) {
+		if (!tape->postponed_rq) {
 			tape->dsc_polling_start = jiffies;
 			tape->dsc_poll_freq = tape->best_dsc_rw_freq;
 			tape->dsc_timeout = jiffies + IDETAPE_DSC_RW_TIMEOUT;
@@ -629,10 +616,12 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
 					tape->dsc_polling_start +
 					IDETAPE_DSC_MA_THRESHOLD))
 			tape->dsc_poll_freq = IDETAPE_DSC_MA_SLOW;
-		idetape_postpone_request(drive);
+		ide_tape_stall_queue(drive);
 		return ide_stopped;
-	} else
+	} else {
 		drive->atapi_flags &= ~IDE_AFLAG_IGNORE_DSC;
+		tape->postponed_rq = false;
+	}
 
 	if (rq->cmd[13] & REQ_IDETAPE_READ) {
 		pc = &tape->queued_pc;
-- 
1.6.3.3


-- 
Regards/Gruss,
    Boris.

Re: [PATCH 3/3] ide-tape: fix handling of postponed rqs

[David Miller]

From: Borislav Petkov <petkovbb@googlemail.com>
Date: Wed, 22 Jul 2009 07:56:57 +0200

> On Tue, Jul 21, 2009 at 08:47:04PM -0700, David Miller wrote:
> 
>> drivers/ide/ide-tape.c: In function ‘ide_tape_stall_queue’:
>> drivers/ide/ide-tape.c:379: warning: unused variable ‘rq’
> 
> Sorry about that, rq is used only in the debug statement and I forgot to
> do a non-debug build, my bad.

Applied, thanks.