tracing: Constify string literal data member in struct trace_event_call

commit 452f4b31e3f70a52b97890888eeb9eaa9a87139a upstream.

The name member of the struct trace_event_call is assigned with
generated string literals; declare them pointer to read-only.

Reported by clang:

    security/landlock/syscalls.c:179:1: warning: initializing 'char *' with an expression of type 'const char[34]' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
      179 | SYSCALL_DEFINE3(landlock_create_ruleset,
          | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      180 |                 const struct landlock_ruleset_attr __user *const, attr,
          |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      181 |                 const size_t, size, const __u32, flags)
          |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/syscalls.h:226:36: note: expanded from macro 'SYSCALL_DEFINE3'
      226 | #define SYSCALL_DEFINE3(name, ...) SYSCALL_DEFINEx(3, _##name, __VA_ARGS__)
          |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/syscalls.h:234:2: note: expanded from macro 'SYSCALL_DEFINEx'
      234 |         SYSCALL_METADATA(sname, x, __VA_ARGS__)                 \
          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/syscalls.h:184:2: note: expanded from macro 'SYSCALL_METADATA'
      184 |         SYSCALL_TRACE_ENTER_EVENT(sname);                       \
          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/syscalls.h:151:30: note: expanded from macro 'SYSCALL_TRACE_ENTER_EVENT'
      151 |                         .name                   = "sys_enter"#sname,    \
          |                                                   ^~~~~~~~~~~~~~~~~

Cc: [email protected]
Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Mickaël Salaün <[email protected]>
Cc: Günther Noack <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Bill Wendling <[email protected]>
Cc: Justin Stitt <[email protected]>
Link: https://lore.kernel.org/[email protected]
Fixes: b77e38a ("tracing: add event trace infrastructure")
Signed-off-by: Christian Göttsche <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: cgzones

include/linux/trace_events.h

@@ -355,7 +355,7 @@ struct trace_event_call {
 	struct list_head	list;
 	struct trace_event_class *class;
 	union {
-		char			*name;
+		const char		*name;
 		/* Set TRACE_EVENT_FL_TRACEPOINT flag when using "tp" */
 		struct tracepoint	*tp;
 	};