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SubjectRe: [PATCH 06/14] tracing: add tracing support for compat syscalls
On Tue, Mar 16, 2010 at 01:46:36PM -0400, Jason Baron wrote:
> #else /* CONFIG_COMPAT */
>
> +#define NR_syscalls_compat 0
> +
> static inline int is_compat_task(void)
> {
> return 0;
> diff --git a/include/trace/syscall.h b/include/trace/syscall.h
> index 8f5ac38..1cc1d1e 100644
> --- a/include/trace/syscall.h
> +++ b/include/trace/syscall.h
> @@ -22,6 +22,7 @@
> struct syscall_metadata {
> const char *name;
> int syscall_nr;
> + int compat_syscall_nr;



Why do you need both syscall_nr and compat_syscall_nr?
Compat and usual syscalls never share the same syscall
metadata.



> +#ifdef __HAVE_ARCH_FTRACE_COMPAT_SYSCALLS
> + if (NR_syscalls_compat) {
> + int match;
> + struct ftrace_event_call *ftrace_event;
> +
> + compat_syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
> + NR_syscalls_compat, GFP_KERNEL);
> + if (!compat_syscalls_metadata) {
> + WARN_ON(1);
> + kfree(syscalls_metadata);
> + return -ENOMEM;
> + }
> + for (i = 0; i < NR_syscalls_compat; i++) {
> + addr = arch_compat_syscall_addr(i);
> + meta = find_syscall_meta(addr);
> + if (!meta)
> + continue;
> +
> + meta->compat_syscall_nr = i;
> + compat_syscalls_metadata[i] = meta;
> + }
> + /* now check if any compat_syscalls are not referenced */
> + for (ftrace_event = __start_ftrace_events;
> + (unsigned long)ftrace_event <
> + (unsigned long)__stop_ftrace_events; ftrace_event++) {



You could reuse for_each_event()



> + match = 0;
> + if (!ftrace_event->name)
> + continue;
> + if (strcmp(ftrace_event->system, "compat_syscalls"))
> + continue;
> + for (i = 0; i < NR_syscalls_compat; i++) {
> + if (ftrace_event->data ==
> + compat_syscalls_metadata[i]) {
> + match = 1;
> + break;


Nano-neat: starting the whole block with if (NR_syscalls_compat)
or making the whole a separate init_ftrace_syscalls() would
have made it win one level of indentation.


> + }
> + }
> + if (!match)
> + ftrace_event->name = NULL;



Nice :)

Thanks.



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