Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 600 insertions, 0 deletions

diff --git a/drivers/scsi/sr_ioctl.c b/drivers/scsi/sr_ioctl.c
new file mode 100644
index 000000000..089653018
--- /dev/null
+++ b/drivers/scsi/sr_ioctl.c
@@ -0,0 +1,600 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/blkdev.h>
+#include <linux/module.h>
+#include <linux/blkpg.h>
+#include <linux/cdrom.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <asm/io.h>
+#include <linux/uaccess.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_ioctl.h>
+#include <scsi/scsi_cmnd.h>
+
+#include "sr.h"
+
+#if 0
+#define DEBUG
+#endif
+
+/* The sr_is_xa() seems to trigger firmware bugs with some drives :-(
+ * It is off by default and can be turned on with this module parameter */
+static int xa_test = 0;
+
+module_param(xa_test, int, S_IRUGO | S_IWUSR);
+
+static int sr_read_tochdr(struct cdrom_device_info *cdi,
+		struct cdrom_tochdr *tochdr)
+{
+	struct scsi_cd *cd = cdi->handle;
+	struct packet_command cgc;
+	int result;
+	unsigned char *buffer;
+
+	buffer = kzalloc(32, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	memset(&cgc, 0, sizeof(struct packet_command));
+	cgc.timeout = IOCTL_TIMEOUT;
+	cgc.cmd[0] = GPCMD_READ_TOC_PMA_ATIP;
+	cgc.cmd[8] = 12;		/* LSB of length */
+	cgc.buffer = buffer;
+	cgc.buflen = 12;
+	cgc.quiet = 1;
+	cgc.data_direction = DMA_FROM_DEVICE;
+
+	result = sr_do_ioctl(cd, &cgc);
+	if (result)
+		goto err;
+
+	tochdr->cdth_trk0 = buffer[2];
+	tochdr->cdth_trk1 = buffer[3];
+
+err:
+	kfree(buffer);
+	return result;
+}
+
+static int sr_read_tocentry(struct cdrom_device_info *cdi,
+		struct cdrom_tocentry *tocentry)
+{
+	struct scsi_cd *cd = cdi->handle;
+	struct packet_command cgc;
+	int result;
+	unsigned char *buffer;
+
+	buffer = kzalloc(32, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	memset(&cgc, 0, sizeof(struct packet_command));
+	cgc.timeout = IOCTL_TIMEOUT;
+	cgc.cmd[0] = GPCMD_READ_TOC_PMA_ATIP;
+	cgc.cmd[1] |= (tocentry->cdte_format == CDROM_MSF) ? 0x02 : 0;
+	cgc.cmd[6] = tocentry->cdte_track;
+	cgc.cmd[8] = 12;		/* LSB of length */
+	cgc.buffer = buffer;
+	cgc.buflen = 12;
+	cgc.data_direction = DMA_FROM_DEVICE;
+
+	result = sr_do_ioctl(cd, &cgc);
+	if (result)
+		goto err;
+
+	tocentry->cdte_ctrl = buffer[5] & 0xf;
+	tocentry->cdte_adr = buffer[5] >> 4;
+	tocentry->cdte_datamode = (tocentry->cdte_ctrl & 0x04) ? 1 : 0;
+	if (tocentry->cdte_format == CDROM_MSF) {
+		tocentry->cdte_addr.msf.minute = buffer[9];
+		tocentry->cdte_addr.msf.second = buffer[10];
+		tocentry->cdte_addr.msf.frame = buffer[11];
+	} else
+		tocentry->cdte_addr.lba = (((((buffer[8] << 8) + buffer[9]) << 8)
+			+ buffer[10]) << 8) + buffer[11];
+
+err:
+	kfree(buffer);
+	return result;
+}
+
+#define IOCTL_RETRIES 3
+
+/* ATAPI drives don't have a SCMD_PLAYAUDIO_TI command.  When these drives
+   are emulating a SCSI device via the idescsi module, they need to have
+   CDROMPLAYTRKIND commands translated into CDROMPLAYMSF commands for them */
+
+static int sr_fake_playtrkind(struct cdrom_device_info *cdi, struct cdrom_ti *ti)
+{
+	struct cdrom_tocentry trk0_te, trk1_te;
+	struct cdrom_tochdr tochdr;
+	struct packet_command cgc;
+	int ntracks, ret;
+
+	ret = sr_read_tochdr(cdi, &tochdr);
+	if (ret)
+		return ret;
+
+	ntracks = tochdr.cdth_trk1 - tochdr.cdth_trk0 + 1;
+	
+	if (ti->cdti_trk1 == ntracks) 
+		ti->cdti_trk1 = CDROM_LEADOUT;
+	else if (ti->cdti_trk1 != CDROM_LEADOUT)
+		ti->cdti_trk1 ++;
+
+	trk0_te.cdte_track = ti->cdti_trk0;
+	trk0_te.cdte_format = CDROM_MSF;
+	trk1_te.cdte_track = ti->cdti_trk1;
+	trk1_te.cdte_format = CDROM_MSF;
+	
+	ret = sr_read_tocentry(cdi, &trk0_te);
+	if (ret)
+		return ret;
+	ret = sr_read_tocentry(cdi, &trk1_te);
+	if (ret)
+		return ret;
+
+	memset(&cgc, 0, sizeof(struct packet_command));
+	cgc.cmd[0] = GPCMD_PLAY_AUDIO_MSF;
+	cgc.cmd[3] = trk0_te.cdte_addr.msf.minute;
+	cgc.cmd[4] = trk0_te.cdte_addr.msf.second;
+	cgc.cmd[5] = trk0_te.cdte_addr.msf.frame;
+	cgc.cmd[6] = trk1_te.cdte_addr.msf.minute;
+	cgc.cmd[7] = trk1_te.cdte_addr.msf.second;
+	cgc.cmd[8] = trk1_te.cdte_addr.msf.frame;
+	cgc.data_direction = DMA_NONE;
+	cgc.timeout = IOCTL_TIMEOUT;
+	return sr_do_ioctl(cdi->handle, &cgc);
+}
+
+static int sr_play_trkind(struct cdrom_device_info *cdi,
+		struct cdrom_ti *ti)
+
+{
+	struct scsi_cd *cd = cdi->handle;
+	struct packet_command cgc;
+	int result;
+
+	memset(&cgc, 0, sizeof(struct packet_command));
+	cgc.timeout = IOCTL_TIMEOUT;
+	cgc.cmd[0] = GPCMD_PLAYAUDIO_TI;
+	cgc.cmd[4] = ti->cdti_trk0;
+	cgc.cmd[5] = ti->cdti_ind0;
+	cgc.cmd[7] = ti->cdti_trk1;
+	cgc.cmd[8] = ti->cdti_ind1;
+	cgc.data_direction = DMA_NONE;
+
+	result = sr_do_ioctl(cd, &cgc);
+	if (result == -EDRIVE_CANT_DO_THIS)
+		result = sr_fake_playtrkind(cdi, ti);
+
+	return result;
+}
+
+/* We do our own retries because we want to know what the specific
+   error code is.  Normally the UNIT_ATTENTION code will automatically
+   clear after one error */
+
+int sr_do_ioctl(Scsi_CD *cd, struct packet_command *cgc)
+{
+	struct scsi_device *SDev;
+	struct scsi_sense_hdr local_sshdr, *sshdr;
+	int result, err = 0, retries = 0;
+	const struct scsi_exec_args exec_args = {
+		.sshdr = cgc->sshdr ? : &local_sshdr,
+	};
+
+	SDev = cd->device;
+
+	sshdr = exec_args.sshdr;
+
+      retry:
+	if (!scsi_block_when_processing_errors(SDev)) {
+		err = -ENODEV;
+		goto out;
+	}
+
+	result = scsi_execute_cmd(SDev, cgc->cmd,
+				  cgc->data_direction == DMA_TO_DEVICE ?
+				  REQ_OP_DRV_OUT : REQ_OP_DRV_IN, cgc->buffer,
+				  cgc->buflen, cgc->timeout, IOCTL_RETRIES,
+				  &exec_args);
+	/* Minimal error checking.  Ignore cases we know about, and report the rest. */
+	if (result < 0) {
+		err = result;
+		goto out;
+	}
+	if (scsi_status_is_check_condition(result)) {
+		switch (sshdr->sense_key) {
+		case UNIT_ATTENTION:
+			SDev->changed = 1;
+			if (!cgc->quiet)
+				sr_printk(KERN_INFO, cd,
+					  "disc change detected.\n");
+			if (retries++ < 10)
+				goto retry;
+			err = -ENOMEDIUM;
+			break;
+		case NOT_READY:	/* This happens if there is no disc in drive */
+			if (sshdr->asc == 0x04 &&
+			    sshdr->ascq == 0x01) {
+				/* sense: Logical unit is in process of becoming ready */
+				if (!cgc->quiet)
+					sr_printk(KERN_INFO, cd,
+						  "CDROM not ready yet.\n");
+				if (retries++ < 10) {
+					/* sleep 2 sec and try again */
+					ssleep(2);
+					goto retry;
+				} else {
+					/* 20 secs are enough? */
+					err = -ENOMEDIUM;
+					break;
+				}
+			}
+			if (!cgc->quiet)
+				sr_printk(KERN_INFO, cd,
+					  "CDROM not ready.  Make sure there "
+					  "is a disc in the drive.\n");
+			err = -ENOMEDIUM;
+			break;
+		case ILLEGAL_REQUEST:
+			err = -EIO;
+			if (sshdr->asc == 0x20 &&
+			    sshdr->ascq == 0x00)
+				/* sense: Invalid command operation code */
+				err = -EDRIVE_CANT_DO_THIS;
+			break;
+		default:
+			err = -EIO;
+		}
+	}
+
+	/* Wake up a process waiting for device */
+      out:
+	cgc->stat = err;
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+/* interface to cdrom.c                                                   */
+
+int sr_tray_move(struct cdrom_device_info *cdi, int pos)
+{
+	Scsi_CD *cd = cdi->handle;
+	struct packet_command cgc;
+
+	memset(&cgc, 0, sizeof(struct packet_command));
+	cgc.cmd[0] = GPCMD_START_STOP_UNIT;
+	cgc.cmd[4] = (pos == 0) ? 0x03 /* close */ : 0x02 /* eject */ ;
+	cgc.data_direction = DMA_NONE;
+	cgc.timeout = IOCTL_TIMEOUT;
+	return sr_do_ioctl(cd, &cgc);
+}
+
+int sr_lock_door(struct cdrom_device_info *cdi, int lock)
+{
+	Scsi_CD *cd = cdi->handle;
+
+	return scsi_set_medium_removal(cd->device, lock ?
+		       SCSI_REMOVAL_PREVENT : SCSI_REMOVAL_ALLOW);
+}
+
+int sr_drive_status(struct cdrom_device_info *cdi, int slot)
+{
+	struct scsi_cd *cd = cdi->handle;
+	struct scsi_sense_hdr sshdr;
+	struct media_event_desc med;
+
+	if (CDSL_CURRENT != slot) {
+		/* we have no changer support */
+		return -EINVAL;
+	}
+	if (!scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr))
+		return CDS_DISC_OK;
+
+	/* SK/ASC/ASCQ of 2/4/1 means "unit is becoming ready" */
+	if (scsi_sense_valid(&sshdr) && sshdr.sense_key == NOT_READY
+			&& sshdr.asc == 0x04 && sshdr.ascq == 0x01)
+		return CDS_DRIVE_NOT_READY;
+
+	if (!cdrom_get_media_event(cdi, &med)) {
+		if (med.media_present)
+			return CDS_DISC_OK;
+		else if (med.door_open)
+			return CDS_TRAY_OPEN;
+		else
+			return CDS_NO_DISC;
+	}
+
+	/*
+	 * SK/ASC/ASCQ of 2/4/2 means "initialization required"
+	 * Using CD_TRAY_OPEN results in an START_STOP_UNIT to close
+	 * the tray, which resolves the initialization requirement.
+	 */
+	if (scsi_sense_valid(&sshdr) && sshdr.sense_key == NOT_READY
+			&& sshdr.asc == 0x04 && sshdr.ascq == 0x02)
+		return CDS_TRAY_OPEN;
+
+	/*
+	 * 0x04 is format in progress .. but there must be a disc present!
+	 */
+	if (sshdr.sense_key == NOT_READY && sshdr.asc == 0x04)
+		return CDS_DISC_OK;
+
+	/*
+	 * If not using Mt Fuji extended media tray reports,
+	 * just return TRAY_OPEN since ATAPI doesn't provide
+	 * any other way to detect this...
+	 */
+	if (scsi_sense_valid(&sshdr) &&
+	    /* 0x3a is medium not present */
+	    sshdr.asc == 0x3a)
+		return CDS_NO_DISC;
+	else
+		return CDS_TRAY_OPEN;
+
+	return CDS_DRIVE_NOT_READY;
+}
+
+int sr_disk_status(struct cdrom_device_info *cdi)
+{
+	Scsi_CD *cd = cdi->handle;
+	struct cdrom_tochdr toc_h;
+	struct cdrom_tocentry toc_e;
+	int i, rc, have_datatracks = 0;
+
+	/* look for data tracks */
+	rc = sr_read_tochdr(cdi, &toc_h);
+	if (rc)
+		return (rc == -ENOMEDIUM) ? CDS_NO_DISC : CDS_NO_INFO;
+
+	for (i = toc_h.cdth_trk0; i <= toc_h.cdth_trk1; i++) {
+		toc_e.cdte_track = i;
+		toc_e.cdte_format = CDROM_LBA;
+		if (sr_read_tocentry(cdi, &toc_e))
+			return CDS_NO_INFO;
+		if (toc_e.cdte_ctrl & CDROM_DATA_TRACK) {
+			have_datatracks = 1;
+			break;
+		}
+	}
+	if (!have_datatracks)
+		return CDS_AUDIO;
+
+	if (cd->xa_flag)
+		return CDS_XA_2_1;
+	else
+		return CDS_DATA_1;
+}
+
+int sr_get_last_session(struct cdrom_device_info *cdi,
+			struct cdrom_multisession *ms_info)
+{
+	Scsi_CD *cd = cdi->handle;
+
+	ms_info->addr.lba = cd->ms_offset;
+	ms_info->xa_flag = cd->xa_flag || cd->ms_offset > 0;
+
+	return 0;
+}
+
+int sr_get_mcn(struct cdrom_device_info *cdi, struct cdrom_mcn *mcn)
+{
+	Scsi_CD *cd = cdi->handle;
+	struct packet_command cgc;
+	char *buffer = kzalloc(32, GFP_KERNEL);
+	int result;
+
+	if (!buffer)
+		return -ENOMEM;
+
+	memset(&cgc, 0, sizeof(struct packet_command));
+	cgc.cmd[0] = GPCMD_READ_SUBCHANNEL;
+	cgc.cmd[2] = 0x40;	/* I do want the subchannel info */
+	cgc.cmd[3] = 0x02;	/* Give me medium catalog number info */
+	cgc.cmd[8] = 24;
+	cgc.buffer = buffer;
+	cgc.buflen = 24;
+	cgc.data_direction = DMA_FROM_DEVICE;
+	cgc.timeout = IOCTL_TIMEOUT;
+	result = sr_do_ioctl(cd, &cgc);
+	if (result)
+		goto err;
+
+	memcpy(mcn->medium_catalog_number, buffer + 9, 13);
+	mcn->medium_catalog_number[13] = 0;
+
+err:
+	kfree(buffer);
+	return result;
+}
+
+int sr_reset(struct cdrom_device_info *cdi)
+{
+	return 0;
+}
+
+int sr_select_speed(struct cdrom_device_info *cdi, unsigned long speed)
+{
+	Scsi_CD *cd = cdi->handle;
+	struct packet_command cgc;
+
+	/* avoid exceeding the max speed or overflowing integer bounds */
+	speed = clamp(speed, 0, 0xffff / 177);
+
+	if (speed == 0)
+		speed = 0xffff;	/* set to max */
+	else
+		speed *= 177;	/* Nx to kbyte/s */
+
+	memset(&cgc, 0, sizeof(struct packet_command));
+	cgc.cmd[0] = GPCMD_SET_SPEED;	/* SET CD SPEED */
+	cgc.cmd[2] = (speed >> 8) & 0xff;	/* MSB for speed (in kbytes/sec) */
+	cgc.cmd[3] = speed & 0xff;	/* LSB */
+	cgc.data_direction = DMA_NONE;
+	cgc.timeout = IOCTL_TIMEOUT;
+
+	if (sr_do_ioctl(cd, &cgc))
+		return -EIO;
+	return 0;
+}
+
+/* ----------------------------------------------------------------------- */
+/* this is called by the generic cdrom driver. arg is a _kernel_ pointer,  */
+/* because the generic cdrom driver does the user access stuff for us.     */
+/* only cdromreadtochdr and cdromreadtocentry are left - for use with the  */
+/* sr_disk_status interface for the generic cdrom driver.                  */
+
+int sr_audio_ioctl(struct cdrom_device_info *cdi, unsigned int cmd, void *arg)
+{
+	switch (cmd) {
+	case CDROMREADTOCHDR:
+		return sr_read_tochdr(cdi, arg);
+	case CDROMREADTOCENTRY:
+		return sr_read_tocentry(cdi, arg);
+	case CDROMPLAYTRKIND:
+		return sr_play_trkind(cdi, arg);
+	default:
+		return -EINVAL;
+	}
+}
+
+/* -----------------------------------------------------------------------
+ * a function to read all sorts of funny cdrom sectors using the READ_CD
+ * scsi-3 mmc command
+ *
+ * lba:     linear block address
+ * format:  0 = data (anything)
+ *          1 = audio
+ *          2 = data (mode 1)
+ *          3 = data (mode 2)
+ *          4 = data (mode 2 form1)
+ *          5 = data (mode 2 form2)
+ * blksize: 2048 | 2336 | 2340 | 2352
+ */
+
+static int sr_read_cd(Scsi_CD *cd, unsigned char *dest, int lba, int format, int blksize)
+{
+	struct packet_command cgc;
+
+#ifdef DEBUG
+	sr_printk(KERN_INFO, cd, "sr_read_cd lba=%d format=%d blksize=%d\n",
+		  lba, format, blksize);
+#endif
+
+	memset(&cgc, 0, sizeof(struct packet_command));
+	cgc.cmd[0] = GPCMD_READ_CD;	/* READ_CD */
+	cgc.cmd[1] = ((format & 7) << 2);
+	cgc.cmd[2] = (unsigned char) (lba >> 24) & 0xff;
+	cgc.cmd[3] = (unsigned char) (lba >> 16) & 0xff;
+	cgc.cmd[4] = (unsigned char) (lba >> 8) & 0xff;
+	cgc.cmd[5] = (unsigned char) lba & 0xff;
+	cgc.cmd[8] = 1;
+	switch (blksize) {
+	case 2336:
+		cgc.cmd[9] = 0x58;
+		break;
+	case 2340:
+		cgc.cmd[9] = 0x78;
+		break;
+	case 2352:
+		cgc.cmd[9] = 0xf8;
+		break;
+	default:
+		cgc.cmd[9] = 0x10;
+		break;
+	}
+	cgc.buffer = dest;
+	cgc.buflen = blksize;
+	cgc.data_direction = DMA_FROM_DEVICE;
+	cgc.timeout = IOCTL_TIMEOUT;
+	return sr_do_ioctl(cd, &cgc);
+}
+
+/*
+ * read sectors with blocksizes other than 2048
+ */
+
+static int sr_read_sector(Scsi_CD *cd, int lba, int blksize, unsigned char *dest)
+{
+	struct packet_command cgc;
+	int rc;
+
+	/* we try the READ CD command first... */
+	if (cd->readcd_known) {
+		rc = sr_read_cd(cd, dest, lba, 0, blksize);
+		if (-EDRIVE_CANT_DO_THIS != rc)
+			return rc;
+		cd->readcd_known = 0;
+		sr_printk(KERN_INFO, cd,
+			  "CDROM doesn't support READ CD (0xbe) command\n");
+		/* fall & retry the other way */
+	}
+	/* ... if this fails, we switch the blocksize using MODE SELECT */
+	if (blksize != cd->device->sector_size) {
+		if (0 != (rc = sr_set_blocklength(cd, blksize)))
+			return rc;
+	}
+#ifdef DEBUG
+	sr_printk(KERN_INFO, cd, "sr_read_sector lba=%d blksize=%d\n",
+		  lba, blksize);
+#endif
+
+	memset(&cgc, 0, sizeof(struct packet_command));
+	cgc.cmd[0] = GPCMD_READ_10;
+	cgc.cmd[2] = (unsigned char) (lba >> 24) & 0xff;
+	cgc.cmd[3] = (unsigned char) (lba >> 16) & 0xff;
+	cgc.cmd[4] = (unsigned char) (lba >> 8) & 0xff;
+	cgc.cmd[5] = (unsigned char) lba & 0xff;
+	cgc.cmd[8] = 1;
+	cgc.buffer = dest;
+	cgc.buflen = blksize;
+	cgc.data_direction = DMA_FROM_DEVICE;
+	cgc.timeout = IOCTL_TIMEOUT;
+	rc = sr_do_ioctl(cd, &cgc);
+
+	if (blksize != CD_FRAMESIZE)
+		rc |= sr_set_blocklength(cd, CD_FRAMESIZE);
+	return rc;
+}
+
+/*
+ * read a sector in raw mode to check the sector format
+ * ret: 1 == mode2 (XA), 0 == mode1, <0 == error 
+ */
+
+int sr_is_xa(Scsi_CD *cd)
+{
+	unsigned char *raw_sector;
+	int is_xa;
+
+	if (!xa_test)
+		return 0;
+
+	raw_sector = kmalloc(2048, GFP_KERNEL);
+	if (!raw_sector)
+		return -ENOMEM;
+	if (0 == sr_read_sector(cd, cd->ms_offset + 16,
+				CD_FRAMESIZE_RAW1, raw_sector)) {
+		is_xa = (raw_sector[3] == 0x02) ? 1 : 0;
+	} else {
+		/* read a raw sector failed for some reason. */
+		is_xa = -1;
+	}
+	kfree(raw_sector);
+#ifdef DEBUG
+	sr_printk(KERN_INFO, cd, "sr_is_xa: %d\n", is_xa);
+#endif
+	return is_xa;
+}