/*
 * Functions used by both the SCSI initiator code and the SCSI target code.
 */

#ifndef _SCSI_COMMON_H_
#define _SCSI_COMMON_H_

#include <linux/types.h>
#include <scsi/scsi_proto.h>

static inline unsigned
scsi_varlen_cdb_length(const void *hdr)
{
	return ((struct scsi_varlen_cdb_hdr *)hdr)->additional_cdb_length + 8;
}

extern const unsigned char scsi_command_size_tbl[8];
#define COMMAND_SIZE(opcode) scsi_command_size_tbl[((opcode) >> 5) & 7]

static inline unsigned
scsi_command_size(const unsigned char *cmnd)
{
	return (cmnd[0] == VARIABLE_LENGTH_CMD) ?
		scsi_varlen_cdb_length(cmnd) : COMMAND_SIZE(cmnd[0]);
}

/* Returns a human-readable name for the device */
extern const char *scsi_device_type(unsigned type);

extern void int_to_scsilun(u64, struct scsi_lun *);
extern u64 scsilun_to_int(struct scsi_lun *);

/*
 * This is a slightly modified SCSI sense "descriptor" format header.
 * The addition is to allow the 0x70 and 0x71 response codes. The idea
 * is to place the salient data from either "fixed" or "descriptor" sense
 * format into one structure to ease application processing.
 *
 * The original sense buffer should be kept around for those cases
 * in which more information is required (e.g. the LBA of a MEDIUM ERROR).
 */
struct scsi_sense_hdr {		/* See SPC-3 section 4.5 */
	u8 response_code;	/* permit: 0x0, 0x70, 0x71, 0x72, 0x73 */
	u8 sense_key;
	u8 asc;
	u8 ascq;
	u8 byte4;
	u8 byte5;
	u8 byte6;
	u8 additional_length;	/* always 0 for fixed sense format */
};

static inline bool scsi_sense_valid(const struct scsi_sense_hdr *sshdr)
{
	if (!sshdr)
		return false;

	return (sshdr->response_code & 0x70) == 0x70;
}

extern bool scsi_normalize_sense(const u8 *sense_buffer, int sb_len,
				 struct scsi_sense_hdr *sshdr);

extern void scsi_build_sense_buffer(int desc, u8 *buf, u8 key, u8 asc, u8 ascq);
int scsi_set_sense_information(u8 *buf, int buf_len, u64 info);
int scsi_set_sense_field_pointer(u8 *buf, int buf_len, u16 fp, u8 bp, bool cd);
extern const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
				       int desc_type);

#endif /* _SCSI_COMMON_H_ */
nds-private-remove&amp;id=9fe7bfce8b3e112e8e08c40deb72ee7e24c6f072'>diff</a></td><td class='form'><form class='right' method='get' action='/cgit.cgi/linux/net-next.git/log/net/dsa/Makefile'>
<input type='hidden' name='h' value='nds-private-remove'/><input type='hidden' name='id' value='9fe7bfce8b3e112e8e08c40deb72ee7e24c6f072'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/log/?h=nds-private-remove&amp;id=9fe7bfce8b3e112e8e08c40deb72ee7e24c6f072'>root</a>/<a href='/cgit.cgi/linux/net-next.git/log/net?h=nds-private-remove&amp;id=9fe7bfce8b3e112e8e08c40deb72ee7e24c6f072'>net</a>/<a href='/cgit.cgi/linux/net-next.git/log/net/dsa?h=nds-private-remove&amp;id=9fe7bfce8b3e112e8e08c40deb72ee7e24c6f072'>dsa</a>/<a href='/cgit.cgi/linux/net-next.git/log/net/dsa/Makefile?h=nds-private-remove&amp;id=9fe7bfce8b3e112e8e08c40deb72ee7e24c6f072'>Makefile</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/cgit.cgi/linux/net-next.git/log/net/dsa/Makefile?h=nds-private-remove&amp;id=9fe7bfce8b3e112e8e08c40deb72ee7e24c6f072&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
<tr><td><span title='2017-02-06 16:53:29 -0500'>2017-02-06</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/net/dsa/Makefile?h=nds-private-remove&amp;id=f515f192ab4f45bb695146b82432d63d98775787'>net: dsa: add switch notifier</a></td><td>Vivien Didelot</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+1</span></td></tr>
n value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;</td><td class='right'>2017-01-28 06:42:20 -0600</td></tr>
<tr><th>committer</th><td>Tejun Heo &lt;tj@kernel.org&gt;</td><td class='right'>2017-01-28 07:49:42 -0500</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/sctp/bind_addr.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/sctp/bind_addr.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>4b96156e3d1dd4dfd6039b7c219c9dc4616da52d</a> /<a href='/cgit.cgi/linux/net-next.git/tree/net/sctp/bind_addr.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>net/sctp/bind_addr.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/sctp/bind_addr.c?h=nds-private-remove&amp;id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/sctp/bind_addr.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341&amp;id2=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>diff</a>)</td></tr></table>
<div class='commit-subject'>percpu-refcount: fix reference leak during percpu-atomic transition</div><div class='commit-msg'>percpu_ref_tryget() and percpu_ref_tryget_live() should return
"true" IFF they acquire a reference. But the return value from
atomic_long_inc_not_zero() is a long and may have high bits set,
e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines
is bool so the reference may actually be acquired but the routines
return "false" which results in a reference leak since the caller
assumes it does not need to do a corresponding percpu_ref_put().

This was seen when performing CPU hotplug during I/O, as hangs in
blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start)
raced with percpu_ref_tryget (blk_mq_timeout_work).
Sample stack trace:

__switch_to+0x2c0/0x450
__schedule+0x2f8/0x970
schedule+0x48/0xc0
blk_mq_freeze_queue_wait+0x94/0x120
blk_mq_queue_reinit_work+0xb8/0x180
blk_mq_queue_reinit_prepare+0x84/0xa0
cpuhp_invoke_callback+0x17c/0x600
cpuhp_up_callbacks+0x58/0x150
_cpu_up+0xf0/0x1c0
do_cpu_up+0x120/0x150
cpu_subsys_online+0x64/0xe0
device_online+0xb4/0x120
online_store+0xb4/0xc0
dev_attr_store+0x68/0xa0
sysfs_kf_write+0x80/0xb0
kernfs_fop_write+0x17c/0x250
__vfs_write+0x6c/0x1e0
vfs_write+0xd0/0x270
SyS_write+0x6c/0x110
system_call+0x38/0xe0

Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS,
and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests.
However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0
and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set.

The fix is to make the tryget routines use an actual boolean internally instead
of the atomic long result truncated to a int.

Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints
Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751
Signed-off-by: Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;
Reviewed-by: Jens Axboe &lt;axboe@fb.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints")
Cc: stable@vger.kernel.org # v3.18+
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>Diffstat</a> (limited to 'net/sctp/bind_addr.c')</div><table summary='diffstat' class='diffstat'>