Hi Andrew,

 The fixed patch is attached. I hope, it's ok this time. 

Thanks,


On 6/27/05, Andrew Morton <akpm@osdl.org> wrote:
> Levent Serinol <lserinol@gmail.com> wrote:
> >
> > This patch enables controlling kernel profiling through proc/sysctl inferface.
> >
> >  With this patch profiling will be available without rebooting the
> >  machine (especially for
> >  production servers) with some drawbacks of vmalloc(tlb). So, bootime
> >  algorithm part is left unchanged for anyone who wishes to use
> >  profiling as usual without tlb drawback by rebooting the machine.
> 
> 
> > --- include/linux/sysctl.h.org        2005-06-13 16:05:17.000000000 +0300
> > +++ include/linux/sysctl.h    2005-06-25 15:05:06.000000000 +0300
> 
> Patches should be in `patch -p1' form, please.  See
> http://www.zip.com.au/~akpm/linux/patches/stuff/tpp.txt
> 
> > +static int prof_on = 0;
> > +static int prof_booton = 0;
> 
> There's no need to explicitly initialise these.
> 
> > +#ifdef CONFIG_SMP
> > +static int remove_hash_tables(void)
> > +{
> > +     int cpu;
> > +
> > +     smp_mb();
> > +     on_each_cpu(profile_nop, NULL, 0, 1);
> 
> Why?
> 
> > +     for_each_online_cpu(cpu) {
> > +             struct page *page;
> > +
> > +             if (per_cpu(cpu_profile_hits, cpu)[0]) {
> > +                     page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
> > +                     per_cpu(cpu_profile_hits, cpu)[0] = NULL;
> > +                     __free_page(page);
> > +             }
> > +             if (per_cpu(cpu_profile_hits, cpu)[1]) {
> > +                     page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
> > +                     per_cpu(cpu_profile_hits, cpu)[1] = NULL;
> > +                     __free_page(page);
> > +             }
> > +     }
> 
> Can this race against itself?  If two cpus run the sysctl at the same time?
> We seem to have lock_kernel() coverage.  It's be nice to do something
> firmer.
> 
> > +int profile_sysctl_handler(ctl_table *table, int write,
> > +     struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
> > +{
> > +     int err;
> > +     struct proc_dir_entry *entry;
> > +
> > +     if (prof_booton && write) return 0;
> > +     err=proc_dointvec(table, write, file, buffer, length, ppos);
> > +     if ((err >= 0) && write) {
> > +     prof_shift = profile_params[1];
> > +     switch(profile_params[0])
> > +     {
> > +     case 0:
> > +             if (prof_on) {
> 
> Coding style is all over the place here, as well as in most of the rest of
> the patch.
> 
> 
>         if (prof_booton && write)
>                 return 0;
>         err = proc_dointvec(table, write, file, buffer, length, ppos);
>         if (err >= 0 && write) {
>                 prof_shift = profile_params[1];
>                 switch (profile_params[0])
>                 {
>                 case 0:
>                         if (prof_on) {
> 
> Every line was changed there...
> 
> Also, doing multiple returns per function is unpopular, although the
> very-early
> 
>         if (foo)
>                 return <something>;
> 
> right at the top of the function is OK.  You can use
> 
>         if (err < 0 || !write)
>                 goto out;
> 
> to save a tab stop.
> 
> > +                  }
> > +             break;
> 
>                 }
>                 break;
> 
> > +     case SCHED_PROFILING || CPU_PROFILING:
> 
> eh?  I'm surprised the compiler swallowed that.  I guess it's the same as
> `case 1:'.  Looks like a bug though.
> 
> > +             if (prof_on) return -1;
> > +             prof_len = (_etext - _stext) >> prof_shift;
> > +             prof_buffer = vmalloc(prof_len*sizeof(atomic_t));
> > +             if (!prof_buffer) return(-ENOMEM);
> > +             if (create_hash_tables()) {
> > +                     vfree(prof_buffer);
> > +                     return -1;
> > +                     }
> > +             prof_on = profile_params[0];
> > +             if (!(entry = create_proc_entry("profile", S_IWUSR | S_IRUGO, NULL))) {
> > +                     remove_hash_tables();
> > +                     vfree(prof_buffer);
> > +                     return 0;
> > +                     }
> > +             entry->proc_fops = &proc_profile_operations;
> > +             entry->size = (1+prof_len) * sizeof(atomic_t);
> > +#ifdef CONFIG_HOTPLUG_CPU
> > +             register_cpu_notifier(&profile_cpu_notifier);
> > +#endif
> > +             profile_discard_flip_buffers();
> > +             memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
> > +                     switch(prof_on)
> > +                     {
> > +                     case SCHED_PROFILING:printk(KERN_INFO
> > +                             "kernel schedule profiling enabled (shift: %ld)\n",
> > +                             prof_shift);
> > +                             break;
> > +                     case CPU_PROFILING:printk(KERN_INFO
> > +                             "kernel profiling enabled (shift: %ld)\n",
> > +                             prof_shift);
> > +                             break;
> > +                             }
> > +                     break;
> > +                     }
> > +             }
> > +     return 0;
> > +}
> 
> Documentation/CodingStyle is your friend ;)
> 
> > --- kernel/sysctl.c.org       2005-06-13 16:05:23.000000000 +0300
> > +++ kernel/sysctl.c   2005-06-26 02:06:23.000000000 +0300
> > ...
> > +extern int profile_params[];
> 
> Try to place this declaration in a header.
> 
> What locking protects prof_boot_on()?  lock_kernel() won't be sufficient
> because we're doing sleeping allocations in here.
> 
> I suspect it would be best to whap a semaphore around the whole thing.
> 


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