Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Wed, 2018-12-19 at 16:01 -0500, Steven Rostedt wrote:
> On Wed, 19 Dec 2018 14:38:39 -0600
> Tom Zanussi wrote:
>
> > On Wed, 2018-12-19 at 15:30 -0500, Steven Rostedt wrote:
> > > On Wed, 19 Dec 2018 12:20:19 -0800
> > > Joe Perches wrote:
> > >
> > > > > Yeah, I had considered it but wasn't sure it was worth it. Since
> > > > > you're suggesting it is, I can send another patch on top of
> > > > > these, or
> > > > > feel free if you want to too. ;-)
> > > >
> > > > I believe the 'strlen("foo") -> sizeof("foo") - 1'
> > > > conversions do not change objects at all.
> > > >
> > > > strlen("constant") is already optimized by gcc to a
> > > > constant value when fed a constant string.
> > >
> > > If that's the case (and it probably is), then yeah, strlen is
> > > probably
> > > better. As it can handle the "not a constant" that you stated in
> > > another email.
> > >
> >
> > OK, so I guess that means we should just drop this patch ('[PATCH 2/7]
> > tracing: Change strlen to sizeof for hist trigger static strings').
> >
>
> No, that patch is fine, the macro was not. I've already applied your
> patch set. Just need to run it through my tests.
The patch included:
- start += strlen("char[");
+ start += sizeof("char[") - 1;
So, that 2/7 patch is unnecessary as there is no object code
change and using 'sizeof("const") - 1' is less intelligible
than strlen("const")
If you convert the strncmp(ptr, "const", strlen("const"))
uses to strncmp_prefix(ptr, "const") eventually, the patch
just makes more variations to change.
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Wed, 19 Dec 2018 12:51:59 -0800 Joe Perches wrote: > > #define strncmp_prefix(str, prefix) \ > > strncmp(str, prefix, strlen(prefix)) > > > > in include/linux/string.h > > > > And go around and use that throughout the kernel. By doing a quick > > grep, I already spotted a few bugs. > > I hope you also convert the existing uses like > > strncmp(str1, "str2", 4) > > where the length value is precalculated to the strlen > of the const string Yeah sure. > > But there seem to be _a lot_ of those... > > $ git grep -P "\bstrncmp\s*\([^,]+,[^,]+,\s*\d+\s*\)" | wc -l > 1681 > Right. I'm going to first create the macro and probably just apply it to the tracing directory. Then when the macro is added to the next merge window, I'll post a bunch of patches that clean up the rest of the code. -- Steve
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Wed, 19 Dec 2018 14:38:39 -0600
Tom Zanussi wrote:
> On Wed, 2018-12-19 at 15:30 -0500, Steven Rostedt wrote:
> > On Wed, 19 Dec 2018 12:20:19 -0800
> > Joe Perches wrote:
> >
> > > > Yeah, I had considered it but wasn't sure it was worth it. Since
> > > > you're suggesting it is, I can send another patch on top of
> > > > these, or
> > > > feel free if you want to too. ;-)
> > >
> > > I believe the 'strlen("foo") -> sizeof("foo") - 1'
> > > conversions do not change objects at all.
> > >
> > > strlen("constant") is already optimized by gcc to a
> > > constant value when fed a constant string.
> >
> > If that's the case (and it probably is), then yeah, strlen is
> > probably
> > better. As it can handle the "not a constant" that you stated in
> > another email.
> >
>
> OK, so I guess that means we should just drop this patch ('[PATCH 2/7]
> tracing: Change strlen to sizeof for hist trigger static strings').
>
No, that patch is fine, the macro was not. I've already applied your
patch set. Just need to run it through my tests.
-- Steve
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Wed, 2018-12-19 at 15:34 -0500, Steven Rostedt wrote:
> On Wed, 19 Dec 2018 12:22:38 -0800
> Joe Perches wrote:
>
> > On Wed, 2018-12-19 at 14:16 -0600, Tom Zanussi wrote:
> > > How's this?
> > >
> > > [PATCH] tracing: Introduce and use strcmp_const() for hist triggers
> > >
> > > Provide a new strcmp_const() macro and make use of it instead of the
> > > longer and more error-prone strncmp(str, "str", sizeof("str") - 1).
> > []
> > > diff --git a/kernel/trace/trace_events_hist.c
> > > b/kernel/trace/trace_events_hist.c
> > []
> > > @@ -22,6 +22,9 @@
> > >
> > > #define STR_VAR_LEN_MAX 32 /* must be multiple of sizeof(u64) */
> > >
> > > +#define strcmp_const(str, str_const) \
> > > + strncmp(str, str_const, sizeof(str_const) - 1)
> >
> > Not good as it's too easy to pass a pointer as str_const
> > and sizeof(pointer) - 1 isn't likely the string length.
>
> Agreed. And I noticed that this is used all over the kernel, so I'm not
> going to add this patch. I'm going to add a:
>
> #define strncmp_prefix(str, prefix) \
> strncmp(str, prefix, strlen(prefix))
>
> in include/linux/string.h
>
> And go around and use that throughout the kernel. By doing a quick
> grep, I already spotted a few bugs.
I hope you also convert the existing uses like
strncmp(str1, "str2", 4)
where the length value is precalculated to the strlen
of the const string
But there seem to be _a lot_ of those...
$ git grep -P "\bstrncmp\s*\([^,]+,[^,]+,\s*\d+\s*\)" | wc -l
1681
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Wed, 2018-12-19 at 15:30 -0500, Steven Rostedt wrote:
> On Wed, 19 Dec 2018 12:20:19 -0800
> Joe Perches wrote:
>
> > > Yeah, I had considered it but wasn't sure it was worth it. Since
> > > you're suggesting it is, I can send another patch on top of
> > > these, or
> > > feel free if you want to too. ;-)
> >
> > I believe the 'strlen("foo") -> sizeof("foo") - 1'
> > conversions do not change objects at all.
> >
> > strlen("constant") is already optimized by gcc to a
> > constant value when fed a constant string.
>
> If that's the case (and it probably is), then yeah, strlen is
> probably
> better. As it can handle the "not a constant" that you stated in
> another email.
>
OK, so I guess that means we should just drop this patch ('[PATCH 2/7]
tracing: Change strlen to sizeof for hist trigger static strings').
Tom
> -- Steve
>
>
> >
> > the strcmp_const macro does seem to make sense as
> > the copy/paste/typo possibility is real.
>
>
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Wed, 19 Dec 2018 12:22:38 -0800
Joe Perches wrote:
> On Wed, 2018-12-19 at 14:16 -0600, Tom Zanussi wrote:
> >
> > How's this?
> >
> > [PATCH] tracing: Introduce and use strcmp_const() for hist triggers
> >
> > Provide a new strcmp_const() macro and make use of it instead of the
> > longer and more error-prone strncmp(str, "str", sizeof("str") - 1).
> []
> > diff --git a/kernel/trace/trace_events_hist.c
> > b/kernel/trace/trace_events_hist.c
> []
> > @@ -22,6 +22,9 @@
> >
> > #define STR_VAR_LEN_MAX32 /* must be multiple of sizeof(u64) */
> >
> > +#define strcmp_const(str, str_const) \
> > + strncmp(str, str_const, sizeof(str_const) - 1)
>
> Not good as it's too easy to pass a pointer as str_const
> and sizeof(pointer) - 1 isn't likely the string length.
Agreed. And I noticed that this is used all over the kernel, so I'm not
going to add this patch. I'm going to add a:
#define strncmp_prefix(str, prefix) \
strncmp(str, prefix, strlen(prefix))
in include/linux/string.h
And go around and use that throughout the kernel. By doing a quick
grep, I already spotted a few bugs.
-- Steve
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Wed, 19 Dec 2018 12:20:19 -0800
Joe Perches wrote:
> > Yeah, I had considered it but wasn't sure it was worth it. Since
> > you're suggesting it is, I can send another patch on top of these, or
> > feel free if you want to too. ;-)
>
> I believe the 'strlen("foo") -> sizeof("foo") - 1'
> conversions do not change objects at all.
>
> strlen("constant") is already optimized by gcc to a
> constant value when fed a constant string.
If that's the case (and it probably is), then yeah, strlen is probably
better. As it can handle the "not a constant" that you stated in
another email.
-- Steve
>
> the strcmp_const macro does seem to make sense as
> the copy/paste/typo possibility is real.
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Wed, 19 Dec 2018 14:16:31 -0600
Tom Zanussi wrote:
> > Yeah, I had considered it but wasn't sure it was worth it. Since
> > you're suggesting it is, I can send another patch on top of these, or
> > feel free if you want to too. ;-)
> >
>
> How's this?
>
> [PATCH] tracing: Introduce and use strcmp_const() for hist triggers
>
> Provide a new strcmp_const() macro and make use of it instead of the
> longer and more error-prone strncmp(str, "str", sizeof("str") - 1).
>
> Idea-and-macro-by: Steve Rostedt
> Signed-off-by: Tom Zanussi
> ---
And I just sent you my version :-) (cross emails).
Note, I changed it to strncmp_const() because it should note that it's
a strncmp() and not an strcmp().
Pretty much identical patches too ;-)
-- Steve
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Wed, 19 Dec 2018 13:46:49 -0600
Tom Zanussi wrote:
> Yeah, I had considered it but wasn't sure it was worth it. Since
> you're suggesting it is, I can send another patch on top of these, or
> feel free if you want to too. ;-)
>
Here, want to ack/review it?
-- Steve
>From 664457f5cc776aa624502bc628285ea6d70ac8c9 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)"
Date: Wed, 19 Dec 2018 15:13:33 -0500
Subject: [PATCH] tracing: Add strncmp_const() macro to prevent typos and cut
paste errors
The trace_events_hist.c file has a lot of strncmp()s of the form:
if (strncmp(str, "constant", sizeof("constant") - 1) == 0)
To prevent typos and errors with the constant string being different from
the string use in sizeof(), and also to condense the code, add a macro that
does this:
#define strncmp_const(str, str_const) \
strncmp(str, str_const, sizeof(str_const) - 1)
Signed-off-by: Steven Rostedt (VMware)
---
kernel/trace/trace_events_hist.c | 32 ++--
1 file changed, 18 insertions(+), 14 deletions(-)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index c5448c103770..40e76053d3d7 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -22,6 +22,10 @@
#define STR_VAR_LEN_MAX32 /* must be multiple of sizeof(u64) */
+/* Safe way to compare string constants (from typos and cut and paste errors)
*/
+#define strncmp_const(str, str_const) \
+ strncmp(str, str_const, sizeof(str_const) - 1)
+
struct hist_field;
typedef u64 (*hist_field_fn_t) (struct hist_field *field,
@@ -1881,8 +1885,8 @@ static int parse_action(char *str, struct
hist_trigger_attrs *attrs)
if (attrs->n_actions >= HIST_ACTIONS_MAX)
return ret;
- if ((strncmp(str, "onmatch(", sizeof("onmatch(") - 1) == 0) ||
- (strncmp(str, "onmax(", sizeof("onmax(") - 1) == 0)) {
+ if ((strncmp_const(str, "onmatch(") == 0) ||
+ (strncmp_const(str, "onmax(") == 0)) {
attrs->action_str[attrs->n_actions] = kstrdup(str, GFP_KERNEL);
if (!attrs->action_str[attrs->n_actions]) {
ret = -ENOMEM;
@@ -1899,34 +1903,34 @@ static int parse_assignment(char *str, struct
hist_trigger_attrs *attrs)
{
int ret = 0;
- if ((strncmp(str, "key=", sizeof("key=") - 1) == 0) ||
- (strncmp(str, "keys=", sizeof("keys=") - 1) == 0)) {
+ if ((strncmp_const(str, "key=") == 0) ||
+ (strncmp_const(str, "keys=") == 0)) {
attrs->keys_str = kstrdup(str, GFP_KERNEL);
if (!attrs->keys_str) {
ret = -ENOMEM;
goto out;
}
- } else if ((strncmp(str, "val=", sizeof("val=") - 1) == 0) ||
-(strncmp(str, "vals=", sizeof("vals=") - 1) == 0) ||
-(strncmp(str, "values=", sizeof("values=") - 1) == 0)) {
+ } else if ((strncmp_const(str, "val=") == 0) ||
+ (strncmp_const(str, "vals=") == 0) ||
+ (strncmp_const(str, "values=") == 0)) {
attrs->vals_str = kstrdup(str, GFP_KERNEL);
if (!attrs->vals_str) {
ret = -ENOMEM;
goto out;
}
- } else if (strncmp(str, "sort=", sizeof("sort=") - 1) == 0) {
+ } else if (strncmp_const(str, "sort=") == 0) {
attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
if (!attrs->sort_key_str) {
ret = -ENOMEM;
goto out;
}
- } else if (strncmp(str, "name=", sizeof("name=") - 1) == 0) {
+ } else if (strncmp_const(str, "name=") == 0) {
attrs->name = kstrdup(str, GFP_KERNEL);
if (!attrs->name) {
ret = -ENOMEM;
goto out;
}
- } else if (strncmp(str, "clock=", sizeof("clock=") - 1) == 0) {
+ } else if (strncmp_const(str, "clock=") == 0) {
strsep(, "=");
if (!str) {
ret = -EINVAL;
@@ -1939,7 +1943,7 @@ static int parse_assignment(char *str, struct
hist_trigger_attrs *attrs)
ret = -ENOMEM;
goto out;
}
- } else if (strncmp(str, "size=", sizeof("size=") - 1) == 0) {
+ } else if (strncmp_const(str, "size=") == 0) {
int map_bits = parse_map_size(str);
if (map_bits < 0) {
@@ -3558,7 +3562,7 @@ static struct action_data *onmax_parse(char *str)
if (!onmax_fn_name || !str)
goto free;
- if (strncmp(onmax_fn_name, "save", sizeof("save") - 1) == 0) {
+ if (strncmp_const(onmax_fn_name, "save") == 0) {
char *params = strsep(, ")");
if (!params) {
@@ -4346,7 +4350,7 @@ static int
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Wed, 2018-12-19 at 14:16 -0600, Tom Zanussi wrote:
>
> How's this?
>
> [PATCH] tracing: Introduce and use strcmp_const() for hist triggers
>
> Provide a new strcmp_const() macro and make use of it instead of the
> longer and more error-prone strncmp(str, "str", sizeof("str") - 1).
[]
> diff --git a/kernel/trace/trace_events_hist.c
> b/kernel/trace/trace_events_hist.c
[]
> @@ -22,6 +22,9 @@
>
> #define STR_VAR_LEN_MAX 32 /* must be multiple of sizeof(u64) */
>
> +#define strcmp_const(str, str_const) \
> + strncmp(str, str_const, sizeof(str_const) - 1)
Not good as it's too easy to pass a pointer as str_const
and sizeof(pointer) - 1 isn't likely the string length.
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Wed, 2018-12-19 at 13:46 -0600, Tom Zanussi wrote:
> Hi Steve,
>
> On Wed, 2018-12-19 at 14:40 -0500, Steven Rostedt wrote:
> > On Tue, 18 Dec 2018 14:33:21 -0600
> > Tom Zanussi wrote:
> >
> > > From: Tom Zanussi
> > >
> > > There's no need to use strlen() for static strings when the length
> > > is
> > > already known, so update trace_events_hist.c with sizeof() for
> > > those
> > > cases.
> > >
> > > Signed-off-by: Tom Zanussi
> > > ---
> > > kernel/trace/trace_events_hist.c | 38 +++-
> > > --
> > > 1 file changed, 19 insertions(+), 19 deletions(-)
> > >
> > > diff --git a/kernel/trace/trace_events_hist.c
> > > b/kernel/trace/trace_events_hist.c
> > > index d29bf8a8e1dd..25d06b3ae1f6 100644
> > > --- a/kernel/trace/trace_events_hist.c
> > > +++ b/kernel/trace/trace_events_hist.c
> > > @@ -507,7 +507,7 @@ static int synth_field_string_size(char *type)
> > > start = strstr(type, "char[");
> > > if (start == NULL)
> > > return -EINVAL;
> > > - start += strlen("char[");
> > > + start += sizeof("char[") - 1;
> > >
> > > end = strchr(type, ']');
> > > if (!end || end < start)
> > > @@ -1843,8 +1843,8 @@ static int parse_action(char *str, struct
> > > hist_trigger_attrs *attrs)
> > > if (attrs->n_actions >= HIST_ACTIONS_MAX)
> > > return ret;
> > >
> > > - if ((strncmp(str, "onmatch(", strlen("onmatch(")) == 0) ||
> > > - (strncmp(str, "onmax(", strlen("onmax(")) == 0)) {
> > > + if ((strncmp(str, "onmatch(", sizeof("onmatch(") - 1) ==
> > > 0) ||
> > > + (strncmp(str, "onmax(", sizeof("onmax(") - 1) == 0)) {
> > > attrs->action_str[attrs->n_actions] = kstrdup(str,
> > > GFP_KERNEL);
> > > if (!attrs->action_str[attrs->n_actions]) {
> > > ret = -ENOMEM;
> > > @@ -1861,34 +1861,34 @@ static int parse_assignment(char *str,
> > > struct hist_trigger_attrs *attrs)
> > > {
> > > int ret = 0;
> > >
> > > - if ((strncmp(str, "key=", strlen("key=")) == 0) ||
> > > - (strncmp(str, "keys=", strlen("keys=")) == 0)) {
> > > + if ((strncmp(str, "key=", sizeof("key=") - 1) == 0) ||
> > > + (strncmp(str, "keys=", sizeof("keys=") - 1) == 0)) {
> > > attrs->keys_str = kstrdup(str, GFP_KERNEL);
> >
> > I'll apply this as is, but since there's a lot of these, I wonder if
> > we
> > should make a marcro for this:
> >
> > #define strcmp_const(str, str_const) strncmp(str, str_const,
> > sizeof(str_const) - 1)
> >
> > ?
> >
> > This would help prevent bugs due to typos and bad cut and paste.
> >
>
> Yeah, I had considered it but wasn't sure it was worth it. Since
> you're suggesting it is, I can send another patch on top of these, or
> feel free if you want to too. ;-)
I believe the 'strlen("foo") -> sizeof("foo") - 1'
conversions do not change objects at all.
strlen("constant") is already optimized by gcc to a
constant value when fed a constant string.
the strcmp_const macro does seem to make sense as
the copy/paste/typo possibility is real.
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Wed, 2018-12-19 at 13:46 -0600, Tom Zanussi wrote:
> Hi Steve,
>
> On Wed, 2018-12-19 at 14:40 -0500, Steven Rostedt wrote:
> > On Tue, 18 Dec 2018 14:33:21 -0600
> > Tom Zanussi wrote:
> >
> > > From: Tom Zanussi
> > >
> > > There's no need to use strlen() for static strings when the
> > > length
> > > is
> > > already known, so update trace_events_hist.c with sizeof() for
> > > those
> > > cases.
> > >
> > > Signed-off-by: Tom Zanussi
> > > ---
> > > kernel/trace/trace_events_hist.c | 38 +++---
> > > --
> > > --
> > > 1 file changed, 19 insertions(+), 19 deletions(-)
> > >
> > > diff --git a/kernel/trace/trace_events_hist.c
> > > b/kernel/trace/trace_events_hist.c
> > > index d29bf8a8e1dd..25d06b3ae1f6 100644
> > > --- a/kernel/trace/trace_events_hist.c
> > > +++ b/kernel/trace/trace_events_hist.c
> > > @@ -507,7 +507,7 @@ static int synth_field_string_size(char
> > > *type)
> > > start = strstr(type, "char[");
> > > if (start == NULL)
> > > return -EINVAL;
> > > - start += strlen("char[");
> > > + start += sizeof("char[") - 1;
> > >
> > > end = strchr(type, ']');
> > > if (!end || end < start)
> > > @@ -1843,8 +1843,8 @@ static int parse_action(char *str, struct
> > > hist_trigger_attrs *attrs)
> > > if (attrs->n_actions >= HIST_ACTIONS_MAX)
> > > return ret;
> > >
> > > - if ((strncmp(str, "onmatch(", strlen("onmatch(")) == 0)
> > > ||
> > > - (strncmp(str, "onmax(", strlen("onmax(")) == 0)) {
> > > + if ((strncmp(str, "onmatch(", sizeof("onmatch(") - 1) ==
> > > 0) ||
> > > + (strncmp(str, "onmax(", sizeof("onmax(") - 1) == 0))
> > > {
> > > attrs->action_str[attrs->n_actions] =
> > > kstrdup(str,
> > > GFP_KERNEL);
> > > if (!attrs->action_str[attrs->n_actions]) {
> > > ret = -ENOMEM;
> > > @@ -1861,34 +1861,34 @@ static int parse_assignment(char *str,
> > > struct hist_trigger_attrs *attrs)
> > > {
> > > int ret = 0;
> > >
> > > - if ((strncmp(str, "key=", strlen("key=")) == 0) ||
> > > - (strncmp(str, "keys=", strlen("keys=")) == 0)) {
> > > + if ((strncmp(str, "key=", sizeof("key=") - 1) == 0) ||
> > > + (strncmp(str, "keys=", sizeof("keys=") - 1) == 0)) {
> > > attrs->keys_str = kstrdup(str, GFP_KERNEL);
> >
> > I'll apply this as is, but since there's a lot of these, I wonder
> > if
> > we
> > should make a marcro for this:
> >
> > #define strcmp_const(str, str_const) strncmp(str, str_const,
> > sizeof(str_const) - 1)
> >
> > ?
> >
> > This would help prevent bugs due to typos and bad cut and paste.
> >
>
> Yeah, I had considered it but wasn't sure it was worth it. Since
> you're suggesting it is, I can send another patch on top of these, or
> feel free if you want to too. ;-)
>
How's this?
[PATCH] tracing: Introduce and use strcmp_const() for hist triggers
Provide a new strcmp_const() macro and make use of it instead of the
longer and more error-prone strncmp(str, "str", sizeof("str") - 1).
Idea-and-macro-by: Steve Rostedt
Signed-off-by: Tom Zanussi
---
kernel/trace/trace_events_hist.c | 31 +--
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index c5448c103770..aaf0d2ac4aab 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -22,6 +22,9 @@
#define STR_VAR_LEN_MAX32 /* must be multiple of sizeof(u64) */
+#define strcmp_const(str, str_const) \
+ strncmp(str, str_const, sizeof(str_const) - 1)
+
struct hist_field;
typedef u64 (*hist_field_fn_t) (struct hist_field *field,
@@ -1881,8 +1884,8 @@ static int parse_action(char *str, struct
hist_trigger_attrs *attrs)
if (attrs->n_actions >= HIST_ACTIONS_MAX)
return ret;
- if ((strncmp(str, "onmatch(", sizeof("onmatch(") - 1) == 0) ||
- (strncmp(str, "onmax(", sizeof("onmax(") - 1) == 0)) {
+ if ((strcmp_const(str, "onmatch(") == 0) ||
+ (strcmp_const(str, "onmax(") == 0)) {
attrs->action_str[attrs->n_actions] = kstrdup(str, GFP_KERNEL);
if (!attrs->action_str[attrs->n_actions]) {
ret = -ENOMEM;
@@ -1899,34 +1902,34 @@ static int parse_assignment(char *str, struct
hist_trigger_attrs *attrs)
{
int ret = 0;
- if ((strncmp(str, "key=", sizeof("key=") - 1) == 0) ||
- (strncmp(str, "keys=", sizeof("keys=") - 1) == 0)) {
+ if ((strcmp_const(str, "key=") == 0) ||
+ (strcmp_const(str, "keys=") == 0)) {
attrs->keys_str = kstrdup(str, GFP_KERNEL);
if (!attrs->keys_str) {
ret = -ENOMEM;
goto out;
}
- } else if ((strncmp(str, "val=", sizeof("val=") - 1) == 0) ||
-(strncmp(str, "vals=", sizeof("vals=") - 1) == 0) ||
-(strncmp(str, "values=",
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
Hi Steve,
On Wed, 2018-12-19 at 14:40 -0500, Steven Rostedt wrote:
> On Tue, 18 Dec 2018 14:33:21 -0600
> Tom Zanussi wrote:
>
> > From: Tom Zanussi
> >
> > There's no need to use strlen() for static strings when the length
> > is
> > already known, so update trace_events_hist.c with sizeof() for
> > those
> > cases.
> >
> > Signed-off-by: Tom Zanussi
> > ---
> > kernel/trace/trace_events_hist.c | 38 +++-
> > --
> > 1 file changed, 19 insertions(+), 19 deletions(-)
> >
> > diff --git a/kernel/trace/trace_events_hist.c
> > b/kernel/trace/trace_events_hist.c
> > index d29bf8a8e1dd..25d06b3ae1f6 100644
> > --- a/kernel/trace/trace_events_hist.c
> > +++ b/kernel/trace/trace_events_hist.c
> > @@ -507,7 +507,7 @@ static int synth_field_string_size(char *type)
> > start = strstr(type, "char[");
> > if (start == NULL)
> > return -EINVAL;
> > - start += strlen("char[");
> > + start += sizeof("char[") - 1;
> >
> > end = strchr(type, ']');
> > if (!end || end < start)
> > @@ -1843,8 +1843,8 @@ static int parse_action(char *str, struct
> > hist_trigger_attrs *attrs)
> > if (attrs->n_actions >= HIST_ACTIONS_MAX)
> > return ret;
> >
> > - if ((strncmp(str, "onmatch(", strlen("onmatch(")) == 0) ||
> > - (strncmp(str, "onmax(", strlen("onmax(")) == 0)) {
> > + if ((strncmp(str, "onmatch(", sizeof("onmatch(") - 1) ==
> > 0) ||
> > + (strncmp(str, "onmax(", sizeof("onmax(") - 1) == 0)) {
> > attrs->action_str[attrs->n_actions] = kstrdup(str,
> > GFP_KERNEL);
> > if (!attrs->action_str[attrs->n_actions]) {
> > ret = -ENOMEM;
> > @@ -1861,34 +1861,34 @@ static int parse_assignment(char *str,
> > struct hist_trigger_attrs *attrs)
> > {
> > int ret = 0;
> >
> > - if ((strncmp(str, "key=", strlen("key=")) == 0) ||
> > - (strncmp(str, "keys=", strlen("keys=")) == 0)) {
> > + if ((strncmp(str, "key=", sizeof("key=") - 1) == 0) ||
> > + (strncmp(str, "keys=", sizeof("keys=") - 1) == 0)) {
> > attrs->keys_str = kstrdup(str, GFP_KERNEL);
>
> I'll apply this as is, but since there's a lot of these, I wonder if
> we
> should make a marcro for this:
>
> #define strcmp_const(str, str_const) strncmp(str, str_const,
> sizeof(str_const) - 1)
>
> ?
>
> This would help prevent bugs due to typos and bad cut and paste.
>
Yeah, I had considered it but wasn't sure it was worth it. Since
you're suggesting it is, I can send another patch on top of these, or
feel free if you want to too. ;-)
Tom
Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings
On Tue, 18 Dec 2018 14:33:21 -0600
Tom Zanussi wrote:
> From: Tom Zanussi
>
> There's no need to use strlen() for static strings when the length is
> already known, so update trace_events_hist.c with sizeof() for those
> cases.
>
> Signed-off-by: Tom Zanussi
> ---
> kernel/trace/trace_events_hist.c | 38 +++---
> 1 file changed, 19 insertions(+), 19 deletions(-)
>
> diff --git a/kernel/trace/trace_events_hist.c
> b/kernel/trace/trace_events_hist.c
> index d29bf8a8e1dd..25d06b3ae1f6 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -507,7 +507,7 @@ static int synth_field_string_size(char *type)
> start = strstr(type, "char[");
> if (start == NULL)
> return -EINVAL;
> - start += strlen("char[");
> + start += sizeof("char[") - 1;
>
> end = strchr(type, ']');
> if (!end || end < start)
> @@ -1843,8 +1843,8 @@ static int parse_action(char *str, struct
> hist_trigger_attrs *attrs)
> if (attrs->n_actions >= HIST_ACTIONS_MAX)
> return ret;
>
> - if ((strncmp(str, "onmatch(", strlen("onmatch(")) == 0) ||
> - (strncmp(str, "onmax(", strlen("onmax(")) == 0)) {
> + if ((strncmp(str, "onmatch(", sizeof("onmatch(") - 1) == 0) ||
> + (strncmp(str, "onmax(", sizeof("onmax(") - 1) == 0)) {
> attrs->action_str[attrs->n_actions] = kstrdup(str, GFP_KERNEL);
> if (!attrs->action_str[attrs->n_actions]) {
> ret = -ENOMEM;
> @@ -1861,34 +1861,34 @@ static int parse_assignment(char *str, struct
> hist_trigger_attrs *attrs)
> {
> int ret = 0;
>
> - if ((strncmp(str, "key=", strlen("key=")) == 0) ||
> - (strncmp(str, "keys=", strlen("keys=")) == 0)) {
> + if ((strncmp(str, "key=", sizeof("key=") - 1) == 0) ||
> + (strncmp(str, "keys=", sizeof("keys=") - 1) == 0)) {
> attrs->keys_str = kstrdup(str, GFP_KERNEL);
I'll apply this as is, but since there's a lot of these, I wonder if we
should make a marcro for this:
#define strcmp_const(str, str_const) strncmp(str, str_const, sizeof(str_const)
- 1)
?
This would help prevent bugs due to typos and bad cut and paste.
-- Steve
> if (!attrs->keys_str) {
> ret = -ENOMEM;
> goto out;
> }
> - } else if ((strncmp(str, "val=", strlen("val=")) == 0) ||
> - (strncmp(str, "vals=", strlen("vals=")) == 0) ||
> - (strncmp(str, "values=", strlen("values=")) == 0)) {
> + } else if ((strncmp(str, "val=", sizeof("val=") - 1) == 0) ||
> + (strncmp(str, "vals=", sizeof("vals=") - 1) == 0) ||
> + (strncmp(str, "values=", sizeof("values=") - 1) == 0)) {
> attrs->vals_str = kstrdup(str, GFP_KERNEL);
> if (!attrs->vals_str) {
> ret = -ENOMEM;
> goto out;
> }
> - } else if (strncmp(str, "sort=", strlen("sort=")) == 0) {
> + } else if (strncmp(str, "sort=", sizeof("sort=") - 1) == 0) {
> attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
> if (!attrs->sort_key_str) {
> ret = -ENOMEM;
> goto out;
> }
> - } else if (strncmp(str, "name=", strlen("name=")) == 0) {
> + } else if (strncmp(str, "name=", sizeof("name=") - 1) == 0) {
> attrs->name = kstrdup(str, GFP_KERNEL);
> if (!attrs->name) {
> ret = -ENOMEM;
> goto out;
> }
> - } else if (strncmp(str, "clock=", strlen("clock=")) == 0) {
> + } else if (strncmp(str, "clock=", sizeof("clock=") - 1) == 0) {
> strsep(, "=");
> if (!str) {
> ret = -EINVAL;
> @@ -1901,7 +1901,7 @@ static int parse_assignment(char *str, struct
> hist_trigger_attrs *attrs)
> ret = -ENOMEM;
> goto out;
> }
> - } else if (strncmp(str, "size=", strlen("size=")) == 0) {
> + } else if (strncmp(str, "size=", sizeof("size=") - 1) == 0) {
> int map_bits = parse_map_size(str);
>
> if (map_bits < 0) {
> @@ -3497,7 +3497,7 @@ static struct action_data *onmax_parse(char *str)
> if (!onmax_fn_name || !str)
> goto free;
>
> - if (strncmp(onmax_fn_name, "save", strlen("save")) == 0) {
> + if (strncmp(onmax_fn_name, "save", sizeof("save") - 1) == 0) {
> char *params = strsep(, ")");
>
> if (!params) {
> @@ -4302,8 +4302,8 @@ static int parse_actions(struct hist_trigger_data
> *hist_data)
> for (i = 0; i < hist_data->attrs->n_actions; i++) {
> str = hist_data->attrs->action_str[i];
>
> - if (strncmp(str, "onmatch(", strlen("onmatch(")) == 0) {
> - char *action_str =
