On Thu, 14 Mar 2024 15:39:28 +0100
Paolo Abeni [off-list ref] wrote:

On Wed, 2024-03-13 at 09:34 -0400, Steven Rostedt wrote:

quoted

From: "Steven Rostedt (Google)" <rostedt@goodmis.org>

[
   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. ;-)

quoted

   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

quoted

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>  

FWIW

Acked-by: Paolo Abeni <pabeni@redhat.com>

Thanks!

-- Steve