* [PATCH] x86, ftrace: Fix compiler warning in ftrace.c
@ 2011-05-12 17:33 Rakib Mullick
2011-05-17 16:04 ` Steven Rostedt
0 siblings, 1 reply; 4+ messages in thread
From: Rakib Mullick @ 2011-05-12 17:33 UTC (permalink / raw)
To: Ingo, Molnar
Cc: hpa, Thomas Gleixner, linux-kernel, x86, Steven Rostedt,
Frederic Weisbecker
Due to commit dc326fca2b64 (x86, cpu: Clean up and unify the NOP selection infrastructure), we get the following warning:
arch/x86/kernel/ftrace.c: In function ‘ftrace_make_nop’:
arch/x86/kernel/ftrace.c:308:6: warning: assignment discards qualifiers from pointer target type
arch/x86/kernel/ftrace.c: In function ‘ftrace_make_call’:
arch/x86/kernel/ftrace.c:318:6: warning: assignment discards qualifiers from pointer target type
ftrace_nop_replace() now returns const unsigned char *, so change its associated function/variable to its compatible type to keep compiler clam.
Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
---
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 0ba15a6..d2d82cf 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -266,8 +266,8 @@ static const unsigned char *ftrace_nop_replace(void)
}
static int
-ftrace_modify_code(unsigned long ip, unsigned char *old_code,
- unsigned char *new_code)
+ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
+ unsigned const char *new_code)
{
unsigned char replaced[MCOUNT_INSN_SIZE];
@@ -290,7 +290,7 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
return -EINVAL;
/* replace the text with the new text */
- if (do_ftrace_mod_code(ip, new_code))
+ if (do_ftrace_mod_code(ip, (void *)new_code))
return -EPERM;
sync_core();
@@ -301,7 +301,7 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
- unsigned char *new, *old;
+ unsigned const char *new, *old;
unsigned long ip = rec->ip;
old = ftrace_call_replace(ip, addr);
@@ -312,7 +312,7 @@ int ftrace_make_nop(struct module *mod,
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
- unsigned char *new, *old;
+ unsigned const char *new, *old;
unsigned long ip = rec->ip;
old = ftrace_nop_replace();
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] x86, ftrace: Fix compiler warning in ftrace.c
2011-05-12 17:33 [PATCH] x86, ftrace: Fix compiler warning in ftrace.c Rakib Mullick
@ 2011-05-17 16:04 ` Steven Rostedt
[not found] ` <BANLkTim2rcr9F=5+C9t-BU8OVfbWw5mFyQ@mail.gmail.com>
0 siblings, 1 reply; 4+ messages in thread
From: Steven Rostedt @ 2011-05-17 16:04 UTC (permalink / raw)
To: Rakib Mullick
Cc: hpa, Thomas Gleixner, linux-kernel, x86, Frederic Weisbecker
On Thu, 2011-05-12 at 23:33 +0600, Rakib Mullick wrote:
> Due to commit dc326fca2b64 (x86, cpu: Clean up and unify the NOP selection infrastructure), we get the following warning:
>
> arch/x86/kernel/ftrace.c: In function ‘ftrace_make_nop’:
> arch/x86/kernel/ftrace.c:308:6: warning: assignment discards qualifiers from pointer target type
> arch/x86/kernel/ftrace.c: In function ‘ftrace_make_call’:
> arch/x86/kernel/ftrace.c:318:6: warning: assignment discards qualifiers from pointer target type
>
> ftrace_nop_replace() now returns const unsigned char *, so change its associated function/variable to its compatible type to keep compiler clam.
>
>
> Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
> ---
>
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index 0ba15a6..d2d82cf 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -266,8 +266,8 @@ static const unsigned char *ftrace_nop_replace(void)
> }
>
> static int
> -ftrace_modify_code(unsigned long ip, unsigned char *old_code,
> - unsigned char *new_code)
> +ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
> + unsigned const char *new_code)
> {
> unsigned char replaced[MCOUNT_INSN_SIZE];
>
> @@ -290,7 +290,7 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
> return -EINVAL;
>
> /* replace the text with the new text */
> - if (do_ftrace_mod_code(ip, new_code))
> + if (do_ftrace_mod_code(ip, (void *)new_code))
Instead of typecasting, why not make new_code const void *?
This would probably trickle down to change __probe_kernel_write() which
would not be a bad thing.
-- Steve
> return -EPERM;
>
> sync_core();
> @@ -301,7 +301,7 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
> int ftrace_make_nop(struct module *mod,
> struct dyn_ftrace *rec, unsigned long addr)
> {
> - unsigned char *new, *old;
> + unsigned const char *new, *old;
> unsigned long ip = rec->ip;
>
> old = ftrace_call_replace(ip, addr);
> @@ -312,7 +312,7 @@ int ftrace_make_nop(struct module *mod,
>
> int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
> {
> - unsigned char *new, *old;
> + unsigned const char *new, *old;
> unsigned long ip = rec->ip;
>
> old = ftrace_nop_replace();
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] x86, ftrace: Fix compiler warning in ftrace.c
[not found] ` <BANLkTim2rcr9F=5+C9t-BU8OVfbWw5mFyQ@mail.gmail.com>
@ 2011-05-17 17:45 ` Steven Rostedt
[not found] ` <BANLkTinUCh_ZbfxEtC4XYOqN_q6_yBq92Q@mail.gmail.com>
0 siblings, 1 reply; 4+ messages in thread
From: Steven Rostedt @ 2011-05-17 17:45 UTC (permalink / raw)
To: Rakib Mullick
Cc: hpa, Thomas Gleixner, linux-kernel, x86, Frederic Weisbecker
On Tue, 2011-05-17 at 23:11 +0600, Rakib Mullick wrote:
>
BTW, You have a weird email client. Causes lots of weird whitespace
> There are other places where they depend on __probe_kernel_write(), it
> might require to change all __probe_kernel_write() callers.
Why would callers of __probe_kernel_write() need to be changed? You can
pass any pointer into a const void*. You just can't do it the other way
around.
-- Steve
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] x86, ftrace: Fix compiler warning in ftrace.c
[not found] ` <BANLkTinUCh_ZbfxEtC4XYOqN_q6_yBq92Q@mail.gmail.com>
@ 2011-05-18 13:30 ` Steven Rostedt
0 siblings, 0 replies; 4+ messages in thread
From: Steven Rostedt @ 2011-05-18 13:30 UTC (permalink / raw)
To: Rakib Mullick
Cc: hpa, Thomas Gleixner, linux-kernel, x86, Frederic Weisbecker
On Wed, 2011-05-18 at 11:02 +0600, Rakib Mullick wrote:
>
>
> Cause, __probe_kernel_write() currently takes void * as its parameter.
> That means all the users of __probe_kernel_write() currently passes
> void *. If we change __probe_kernel_write's parameter ( src) from void
> * to const void * , then all the callers also needs to do that. Isn't
> it?
No.
Look at __probe_kernel_write() itself. It calls
__copy_to_user_in_atomic() which takes const void *src, where we pass in
void *src. That __probe_kernel_write() having void *src is actually a
bug.
Make that a separate patch, or maybe I'll just do it.
-- Steve
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2011-05-18 13:30 UTC | newest]
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2011-05-12 17:33 [PATCH] x86, ftrace: Fix compiler warning in ftrace.c Rakib Mullick
2011-05-17 16:04 ` Steven Rostedt
[not found] ` <BANLkTim2rcr9F=5+C9t-BU8OVfbWw5mFyQ@mail.gmail.com>
2011-05-17 17:45 ` Steven Rostedt
[not found] ` <BANLkTinUCh_ZbfxEtC4XYOqN_q6_yBq92Q@mail.gmail.com>
2011-05-18 13:30 ` Steven Rostedt
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