Re: [PATCH] net: hns3: tracing: fix hclgevf trace event strings

[Steven Rostedt]

On Thu, 14 Mar 2024 15:39:28 +0100
Paolo Abeni <pabeni@xxxxxxxxxx> wrote:

> On Wed, 2024-03-13 at 09:34 -0400, Steven Rostedt wrote:
> > From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
> > 
> > [
> >    Note, I need to take this patch through my tree, so I'm looking for acks.  
> 
> Note that this device driver is changing quite rapidly, so I expect
> some conflicts here later. I guess Liuns will have to handle them ;)

Well, it merges fine with linux-next and linus's current master. ;-)

> 
> >    This causes the build to fail when I add the __assign_str() check, which
> >    I was about to push to Linus, but it breaks allmodconfig due to this error.
> > ]
> > 
> > The __string() and __assign_str() helper macros of the TRACE_EVENT() macro
> > are going through some optimizations where only the source string of
> > __string() will be used and the __assign_str() source will be ignored and
> > later removed.
> > 
> > To make sure that there's no issues, a new check is added between the
> > __string() src argument and the __assign_str() src argument that does a
> > strcmp() to make sure they are the same string.
> > 
> > The hclgevf trace events have:
> > 
> >   __assign_str(devname, &hdev->nic.kinfo.netdev->name);
> > 
> > Which triggers the warning:
> > 
> > hclgevf_trace.h:34:39: error: passing argument 1 of ‘strcmp’ from incompatible pointer type [-Werror=incompatible-pointer-types]
> >    34 |                 __assign_str(devname, &hdev->nic.kinfo.netdev->name);
> >  [..]
> > arch/x86/include/asm/string_64.h:75:24: note: expected ‘const char *’ but argument is of type ‘char (*)[16]’
> >    75 | int strcmp(const char *cs, const char *ct);
> >       |            ~~~~~~~~~~~~^~
> > 
> > 
> > Because __assign_str() now has:
> > 
> > 	WARN_ON_ONCE(__builtin_constant_p(src) ?		\
> > 		     strcmp((src), __data_offsets.dst##_ptr_) :	\
> > 		     (src) != __data_offsets.dst##_ptr_);	\
> > 
> > The problem is the '&' on hdev->nic.kinfo.netdev->name. That's because
> > that name is:
> > 
> > 	char			name[IFNAMSIZ]
> > 
> > Where passing an address '&' of a char array is not compatible with strcmp().
> > 
> > The '&' is not necessary, remove it.
> > 
> > Fixes: d8355240cf8fb ("net: hns3: add trace event support for PF/VF mailbox")  
> 
> checkpactch in strict mode complains the hash is not 12 char long.

Hmm, I wonder why my git blame gives me 13 characters in the sha. (I cut
and pasted it from git blame). My git config has:

[core]  
        abbrev = 12


> 
> > Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>  
> 
> FWIW
> 
> Acked-by: Paolo Abeni <pabeni@xxxxxxxxxx>

Thanks!

-- Steve