Revision 3b6b7813b198b578aa7e04e4047ddb8225c37b7f authored by Mikulas Patocka on 20 March 2013, 17:21:25 UTC, committed by Alasdair G Kergon on 20 March 2013, 17:21:25 UTC
A deadlock was found in the prefetch code in the dm verity map function. This patch fixes this by transferring the prefetch to a worker thread and skipping it completely if kmalloc fails. If generic_make_request is called recursively, it queues the I/O request on the current->bio_list without making the I/O request and returns. The routine making the recursive call cannot wait for the I/O to complete. The deadlock occurs when one thread grabs the bufio_client mutex and waits for an I/O to complete but the I/O is queued on another thread's current->bio_list and is waiting to get the mutex held by the first thread. The fix recognises that prefetching is not essential. If memory can be allocated, it queues the prefetch request to the worker thread, but if not, it does nothing. Signed-off-by: Paul Taysom <taysom@chromium.org> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: stable@kernel.org
1 parent 58051b9
hexdump.c
/*
* lib/hexdump.c
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation. See README and COPYING for
* more details.
*/
#include <linux/types.h>
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/export.h>
const char hex_asc[] = "0123456789abcdef";
EXPORT_SYMBOL(hex_asc);
/**
* hex_to_bin - convert a hex digit to its real value
* @ch: ascii character represents hex digit
*
* hex_to_bin() converts one hex digit to its actual value or -1 in case of bad
* input.
*/
int hex_to_bin(char ch)
{
if ((ch >= '0') && (ch <= '9'))
return ch - '0';
ch = tolower(ch);
if ((ch >= 'a') && (ch <= 'f'))
return ch - 'a' + 10;
return -1;
}
EXPORT_SYMBOL(hex_to_bin);
/**
* hex2bin - convert an ascii hexadecimal string to its binary representation
* @dst: binary result
* @src: ascii hexadecimal string
* @count: result length
*
* Return 0 on success, -1 in case of bad input.
*/
int hex2bin(u8 *dst, const char *src, size_t count)
{
while (count--) {
int hi = hex_to_bin(*src++);
int lo = hex_to_bin(*src++);
if ((hi < 0) || (lo < 0))
return -1;
*dst++ = (hi << 4) | lo;
}
return 0;
}
EXPORT_SYMBOL(hex2bin);
/**
* hex_dump_to_buffer - convert a blob of data to "hex ASCII" in memory
* @buf: data blob to dump
* @len: number of bytes in the @buf
* @rowsize: number of bytes to print per line; must be 16 or 32
* @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
* @linebuf: where to put the converted data
* @linebuflen: total size of @linebuf, including space for terminating NUL
* @ascii: include ASCII after the hex output
*
* hex_dump_to_buffer() works on one "line" of output at a time, i.e.,
* 16 or 32 bytes of input data converted to hex + ASCII output.
*
* Given a buffer of u8 data, hex_dump_to_buffer() converts the input data
* to a hex + ASCII dump at the supplied memory location.
* The converted output is always NUL-terminated.
*
* E.g.:
* hex_dump_to_buffer(frame->data, frame->len, 16, 1,
* linebuf, sizeof(linebuf), true);
*
* example output buffer:
* 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO
*/
void hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
int groupsize, char *linebuf, size_t linebuflen,
bool ascii)
{
const u8 *ptr = buf;
u8 ch;
int j, lx = 0;
int ascii_column;
if (rowsize != 16 && rowsize != 32)
rowsize = 16;
if (!len)
goto nil;
if (len > rowsize) /* limit to one line at a time */
len = rowsize;
if ((len % groupsize) != 0) /* no mixed size output */
groupsize = 1;
switch (groupsize) {
case 8: {
const u64 *ptr8 = buf;
int ngroups = len / groupsize;
for (j = 0; j < ngroups; j++)
lx += scnprintf(linebuf + lx, linebuflen - lx,
"%s%16.16llx", j ? " " : "",
(unsigned long long)*(ptr8 + j));
ascii_column = 17 * ngroups + 2;
break;
}
case 4: {
const u32 *ptr4 = buf;
int ngroups = len / groupsize;
for (j = 0; j < ngroups; j++)
lx += scnprintf(linebuf + lx, linebuflen - lx,
"%s%8.8x", j ? " " : "", *(ptr4 + j));
ascii_column = 9 * ngroups + 2;
break;
}
case 2: {
const u16 *ptr2 = buf;
int ngroups = len / groupsize;
for (j = 0; j < ngroups; j++)
lx += scnprintf(linebuf + lx, linebuflen - lx,
"%s%4.4x", j ? " " : "", *(ptr2 + j));
ascii_column = 5 * ngroups + 2;
break;
}
default:
for (j = 0; (j < len) && (lx + 3) <= linebuflen; j++) {
ch = ptr[j];
linebuf[lx++] = hex_asc_hi(ch);
linebuf[lx++] = hex_asc_lo(ch);
linebuf[lx++] = ' ';
}
if (j)
lx--;
ascii_column = 3 * rowsize + 2;
break;
}
if (!ascii)
goto nil;
while (lx < (linebuflen - 1) && lx < (ascii_column - 1))
linebuf[lx++] = ' ';
for (j = 0; (j < len) && (lx + 2) < linebuflen; j++) {
ch = ptr[j];
linebuf[lx++] = (isascii(ch) && isprint(ch)) ? ch : '.';
}
nil:
linebuf[lx++] = '\0';
}
EXPORT_SYMBOL(hex_dump_to_buffer);
#ifdef CONFIG_PRINTK
/**
* print_hex_dump - print a text hex dump to syslog for a binary blob of data
* @level: kernel log level (e.g. KERN_DEBUG)
* @prefix_str: string to prefix each line with;
* caller supplies trailing spaces for alignment if desired
* @prefix_type: controls whether prefix of an offset, address, or none
* is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)
* @rowsize: number of bytes to print per line; must be 16 or 32
* @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
* @buf: data blob to dump
* @len: number of bytes in the @buf
* @ascii: include ASCII after the hex output
*
* Given a buffer of u8 data, print_hex_dump() prints a hex + ASCII dump
* to the kernel log at the specified kernel log level, with an optional
* leading prefix.
*
* print_hex_dump() works on one "line" of output at a time, i.e.,
* 16 or 32 bytes of input data converted to hex + ASCII output.
* print_hex_dump() iterates over the entire input @buf, breaking it into
* "line size" chunks to format and print.
*
* E.g.:
* print_hex_dump(KERN_DEBUG, "raw data: ", DUMP_PREFIX_ADDRESS,
* 16, 1, frame->data, frame->len, true);
*
* Example output using %DUMP_PREFIX_OFFSET and 1-byte mode:
* 0009ab42: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO
* Example output using %DUMP_PREFIX_ADDRESS and 4-byte mode:
* ffffffff88089af0: 73727170 77767574 7b7a7978 7f7e7d7c pqrstuvwxyz{|}~.
*/
void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
int rowsize, int groupsize,
const void *buf, size_t len, bool ascii)
{
const u8 *ptr = buf;
int i, linelen, remaining = len;
unsigned char linebuf[32 * 3 + 2 + 32 + 1];
if (rowsize != 16 && rowsize != 32)
rowsize = 16;
for (i = 0; i < len; i += rowsize) {
linelen = min(remaining, rowsize);
remaining -= rowsize;
hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
linebuf, sizeof(linebuf), ascii);
switch (prefix_type) {
case DUMP_PREFIX_ADDRESS:
printk("%s%s%p: %s\n",
level, prefix_str, ptr + i, linebuf);
break;
case DUMP_PREFIX_OFFSET:
printk("%s%s%.8x: %s\n", level, prefix_str, i, linebuf);
break;
default:
printk("%s%s%s\n", level, prefix_str, linebuf);
break;
}
}
}
EXPORT_SYMBOL(print_hex_dump);
#if !defined(CONFIG_DYNAMIC_DEBUG)
/**
* print_hex_dump_bytes - shorthand form of print_hex_dump() with default params
* @prefix_str: string to prefix each line with;
* caller supplies trailing spaces for alignment if desired
* @prefix_type: controls whether prefix of an offset, address, or none
* is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)
* @buf: data blob to dump
* @len: number of bytes in the @buf
*
* Calls print_hex_dump(), with log level of KERN_DEBUG,
* rowsize of 16, groupsize of 1, and ASCII output included.
*/
void print_hex_dump_bytes(const char *prefix_str, int prefix_type,
const void *buf, size_t len)
{
print_hex_dump(KERN_DEBUG, prefix_str, prefix_type, 16, 1,
buf, len, true);
}
EXPORT_SYMBOL(print_hex_dump_bytes);
#endif /* !defined(CONFIG_DYNAMIC_DEBUG) */
#endif /* defined(CONFIG_PRINTK) */
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