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dev_dbg/dynamic_debug: Update to use printk_emit, optimize stack
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commit c4e00da
("driver-core: extend dev_printk() to pass structured data")
changed __dev_printk and broke dynamic-debug's ability to control the
dynamic prefix of dev_dbg(dev,..).

commit af7f215
("drivers-core: make structured logging play nice with dynamic-debug")
made a minimal correction.

The current dynamic debug code uses up to 3 recursion levels via %pV.
This can consume quite a bit of stack.  Directly call printk_emit to
reduce the recursion depth.

These changes include:

dev_dbg:
o Create and use function create_syslog_header to format the syslog
  header for printk_emit uses.
o Call create_syslog_header and neaten __dev_printk
o Make __dev_printk static not global
o Remove include header declaration of __dev_printk
o Remove now unused EXPORT_SYMBOL() of __dev_printk
o Whitespace neatening

dynamic_dev_dbg:
o Remove KERN_DEBUG from dynamic_emit_prefix
o Call create_syslog_header and printk_emit
o Whitespace neatening

Signed-off-by: Joe Perches <[email protected]>
Acked-by: David S. Miller <[email protected]>
Tested-by: Jim Cromie <[email protected]>
Acked-by: Jason Baron <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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@JoePerches @gregkh
JoePerches authored and gregkh committed Sep 17, 2012
1 parent 8f949b9 commit 798efc6
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Showing 3 changed files with 67 additions and 44 deletions.
64 changes: 34 additions & 30 deletions drivers/base/core.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1865,26 +1865,19 @@ void device_shutdown(void)
*/

#ifdef CONFIG_PRINTK
int __dev_printk(const char *level, const struct device *dev,
struct va_format *vaf)
int create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen)
{
char dict[128];
const char *level_extra = "";
size_t dictlen = 0;
const char *subsys;

if (!dev)
return printk("%s(NULL device *): %pV", level, vaf);
size_t pos = 0;

if (dev->class)
subsys = dev->class->name;
else if (dev->bus)
subsys = dev->bus->name;
else
goto skip;
return 0;

dictlen += snprintf(dict + dictlen, sizeof(dict) - dictlen,
"SUBSYSTEM=%s", subsys);
pos += snprintf(hdr + pos, hdrlen - pos, "SUBSYSTEM=%s", subsys);

/*
* Add device identifier DEVICE=:
Expand All @@ -1900,32 +1893,41 @@ int __dev_printk(const char *level, const struct device *dev,
c = 'b';
else
c = 'c';
dictlen++;
dictlen += snprintf(dict + dictlen, sizeof(dict) - dictlen,
"DEVICE=%c%u:%u",
c, MAJOR(dev->devt), MINOR(dev->devt));
pos++;
pos += snprintf(hdr + pos, hdrlen - pos,
"DEVICE=%c%u:%u",
c, MAJOR(dev->devt), MINOR(dev->devt));
} else if (strcmp(subsys, "net") == 0) {
struct net_device *net = to_net_dev(dev);

dictlen++;
dictlen += snprintf(dict + dictlen, sizeof(dict) - dictlen,
"DEVICE=n%u", net->ifindex);
pos++;
pos += snprintf(hdr + pos, hdrlen - pos,
"DEVICE=n%u", net->ifindex);
} else {
dictlen++;
dictlen += snprintf(dict + dictlen, sizeof(dict) - dictlen,
"DEVICE=+%s:%s", subsys, dev_name(dev));
pos++;
pos += snprintf(hdr + pos, hdrlen - pos,
"DEVICE=+%s:%s", subsys, dev_name(dev));
}
skip:
if (level[2])
level_extra = &level[2]; /* skip past KERN_SOH "L" */

return printk_emit(0, level[1] - '0',
dictlen ? dict : NULL, dictlen,
"%s %s: %s%pV",
dev_driver_string(dev), dev_name(dev),
level_extra, vaf);
return pos;
}
EXPORT_SYMBOL(create_syslog_header);

static int __dev_printk(const char *level, const struct device *dev,
struct va_format *vaf)
{
char hdr[128];
size_t hdrlen;

if (!dev)
return printk("%s(NULL device *): %pV", level, vaf);

hdrlen = create_syslog_header(dev, hdr, sizeof(hdr));

return printk_emit(0, level[1] - '0', hdrlen ? hdr : NULL, hdrlen,
"%s %s: %pV",
dev_driver_string(dev), dev_name(dev), vaf);
}
EXPORT_SYMBOL(__dev_printk);

int dev_printk(const char *level, const struct device *dev,
const char *fmt, ...)
Expand All @@ -1940,6 +1942,7 @@ int dev_printk(const char *level, const struct device *dev,
vaf.va = &args;

r = __dev_printk(level, dev, &vaf);

va_end(args);

return r;
Expand All @@ -1959,6 +1962,7 @@ int func(const struct device *dev, const char *fmt, ...) \
vaf.va = &args; \
\
r = __dev_printk(kern_level, dev, &vaf); \
\
va_end(args); \
\
return r; \
Expand Down
8 changes: 4 additions & 4 deletions include/linux/device.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -895,12 +895,12 @@ extern const char *dev_driver_string(const struct device *dev);

#ifdef CONFIG_PRINTK

extern int __dev_printk(const char *level, const struct device *dev,
struct va_format *vaf);
extern int create_syslog_header(const struct device *dev,
char *hdr, size_t hdrlen);

extern __printf(3, 4)
int dev_printk(const char *level, const struct device *dev,
const char *fmt, ...)
;
const char *fmt, ...);
extern __printf(2, 3)
int dev_emerg(const struct device *dev, const char *fmt, ...);
extern __printf(2, 3)
Expand Down
39 changes: 29 additions & 10 deletions lib/dynamic_debug.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -521,25 +521,25 @@ static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
int pos_after_tid;
int pos = 0;

pos += snprintf(buf + pos, remaining(pos), "%s", KERN_DEBUG);
*buf = '\0';

if (desc->flags & _DPRINTK_FLAGS_INCL_TID) {
if (in_interrupt())
pos += snprintf(buf + pos, remaining(pos), "%s ",
"<intr>");
pos += snprintf(buf + pos, remaining(pos), "<intr> ");
else
pos += snprintf(buf + pos, remaining(pos), "[%d] ",
task_pid_vnr(current));
task_pid_vnr(current));
}
pos_after_tid = pos;
if (desc->flags & _DPRINTK_FLAGS_INCL_MODNAME)
pos += snprintf(buf + pos, remaining(pos), "%s:",
desc->modname);
desc->modname);
if (desc->flags & _DPRINTK_FLAGS_INCL_FUNCNAME)
pos += snprintf(buf + pos, remaining(pos), "%s:",
desc->function);
desc->function);
if (desc->flags & _DPRINTK_FLAGS_INCL_LINENO)
pos += snprintf(buf + pos, remaining(pos), "%d:",
desc->lineno);
desc->lineno);
if (pos - pos_after_tid)
pos += snprintf(buf + pos, remaining(pos), " ");
if (pos >= PREFIX_SIZE)
Expand All @@ -559,9 +559,13 @@ int __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...)
BUG_ON(!fmt);

va_start(args, fmt);

vaf.fmt = fmt;
vaf.va = &args;
res = printk("%s%pV", dynamic_emit_prefix(descriptor, buf), &vaf);

res = printk(KERN_DEBUG "%s%pV",
dynamic_emit_prefix(descriptor, buf), &vaf);

va_end(args);

return res;
Expand All @@ -574,15 +578,30 @@ int __dynamic_dev_dbg(struct _ddebug *descriptor,
struct va_format vaf;
va_list args;
int res;
char buf[PREFIX_SIZE];

BUG_ON(!descriptor);
BUG_ON(!fmt);

va_start(args, fmt);

vaf.fmt = fmt;
vaf.va = &args;
res = __dev_printk(dynamic_emit_prefix(descriptor, buf), dev, &vaf);

if (!dev) {
res = printk(KERN_DEBUG "(NULL device *): %pV", &vaf);
} else {
char buf[PREFIX_SIZE];
char dict[128];
size_t dictlen;

dictlen = create_syslog_header(dev, dict, sizeof(dict));

res = printk_emit(0, 7, dictlen ? dict : NULL, dictlen,
"%s%s %s: %pV",
dynamic_emit_prefix(descriptor, buf),
dev_driver_string(dev), dev_name(dev), &vaf);
}

va_end(args);

return res;
Expand Down

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