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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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