Messages in this thread | | | Subject | Re: kfree(NULL) | From | Daniel Walker <> | Date | Fri, 21 Apr 2006 14:11:08 -0700 |
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I've been working on some code that records all the data for output to a proc entry . It's pretty light weight .. I'll send it once it's finished ..
Daniel
On Fri, 2006-04-21 at 14:02 -0700, Hua Zhong wrote: > Maybe something like this might be a useful debug option to detect unwise likely()/unlikely() usage? > > This is a quick hack (not submitted for inclusion), but it works on my box and detected certain points after boot. Anyone likes this idea? > > The reason I had to add printk_debug_likely() is that using printk directly gives compile error. It seems not to like asmlinkage for some reason..I guess likely/unlikely are too fundamental macros and the dependency gets too messy. Or maybe it could be fixed in a way I've not found. > > It increases kernel size by about 10%, but hey, it's a debugg option. :-) > > Sample print: > > possible (un)likely misuse at include/asm/mmu_context.h:32/switch_mm() > <c011b644> printk_debug_likely+0x25/0x31 <c02b3092> schedule+0xb04/0xefa > <c02b457b> __mutex_lock_slowpath+0x35a/0x89e <c016c0fd> real_lookup+0x1f/0xb3 > <c016c0fd> real_lookup+0x1f/0xb3 <c016c512> do_lookup+0x50/0xe8 > <c016d14b> __link_path_walk+0xba1/0x125f <c016d8a6> link_path_walk+0x9d/0x166 > <c014b911> __handle_mm_fault+0x2fd/0x35b <c01ca29e> _atomic_dec_and_lock+0x22/0x2c > <c016d5c2> __link_path_walk+0x1018/0x125f <c016d8a6> link_path_walk+0x9d/0x166 > <c014b911> __handle_mm_fault+0x2fd/0x35b <c01ce9fe> strncpy_from_user+0x94/0xb3 > <c016dee7> do_path_lookup+0x35c/0x4d2 <c016e385> __user_walk_fd+0x84/0x9b > <c0167ae1> vfs_stat_fd+0x15/0x3c <c014b911> __handle_mm_fault+0x2fd/0x35b > <c0168091> sys_stat64+0xf/0x23 <c0113fea> do_page_fault+0x30d/0x753 > <c01ceefd> copy_to_user+0x113/0x11c <c0126ee6> sys_rt_sigprocmask+0xae/0xc1 > <c01035cb> sysenter_past_esp+0x54/0x75 > possible (un)likely misuse at kernel/sched.c:1638/context_switch() > <c011b644> printk_debug_likely+0x25/0x31 <c02b3025> schedule+0xa97/0xefa > <c011ddcd> do_exit+0x75b/0x765 <c011dec4> sys_exit_group+0x0/0xd > <c01035cb> sysenter_past_esp+0x54/0x75 > possible (un)likely misuse at kernel/softlockup.c:59/softlockup_tick() > <c011b644> printk_debug_likely+0x25/0x31 <c0138f78> softlockup_tick+0x88/0xf5 > <c0123dcd> update_process_times+0x35/0x57 <c0106133> timer_interrupt+0x3d/0x60 > <c013919c> handle_IRQ_event+0x21/0x4a <c01392f7> __do_IRQ+0x132/0x1e7 > <c0104d86> do_IRQ+0x9c/0xab <c01037fe> common_interrupt+0x1a/0x20 > possible (un)likely misuse at kernel/sched.c:1645/context_switch() > <c011b644> printk_debug_likely+0x25/0x31 <c02b3236> schedule+0xca8/0xefa > <c0130d33> enqueue_hrtimer+0x5b/0x80 <c02b57f5> do_nanosleep+0x3b/0xc0 > <c0131092> hrtimer_nanosleep+0x45/0xe6 <c01680b4> sys_lstat64+0xf/0x23 > <c013102a> hrtimer_wakeup+0x0/0x18 <c01cf021> copy_from_user+0x11b/0x142 > <c0131179> sys_nanosleep+0x46/0x4e <c01035cb> sysenter_past_esp+0x54/0x75 > > diff --git a/include/linux/compiler.h b/include/linux/compiler.h > index f23d3c6..a6df5f7 100644 > --- a/include/linux/compiler.h > +++ b/include/linux/compiler.h > @@ -58,9 +58,32 @@ #endif > * build go below this comment. Actual compiler/compiler version > * specific implementations come from the above header files > */ > +#define CONFIG_DEBUG_LIKELY > +#ifdef CONFIG_DEBUG_LIKELY > +extern int printk_debug_likely(const char *fmt, ...); > +extern int debug_likely_count_min_thresh; > +extern int debug_likely_print_max_thresh; > +#define __check_likely(x, v, uv) \ > + ({ static int _ckl_print_nr = 0; \ > + static unsigned int _ckl_s[2]; \ > + int _ckl_r = !!(x); \ > + _ckl_s[_ckl_r]++; \ > + if ((_ckl_s[v] == _ckl_s[uv]) && (_ckl_s[v] > debug_likely_count_min_thresh) \ > + && (_ckl_print_nr < debug_likely_print_max_thresh)) { \ > + _ckl_print_nr++; \ > + printk_debug_likely("possible (un)likely misuse at %s:%d/%s()\n", \ > + __FILE__, __LINE__, __FUNCTION__); \ > + } \ > + _ckl_r; }) > +#else > +#define __check_likely(x, v, uv) __builtin_expect(!!(x), v) > +#endif > + > +#define likely(x) __check_likely(x, 1, 0) > +#define unlikely(x) __check_likely(x, 0, 1) > > -#define likely(x) __builtin_expect(!!(x), 1) > -#define unlikely(x) __builtin_expect(!!(x), 0) > +//#define likely(x) __builtin_expect(!!(x), 1) > +//#define unlikely(x) __builtin_expect(!!(x), 0) > > /* Optimization barrier */ > #ifndef barrier > diff --git a/kernel/printk.c b/kernel/printk.c > index c056f33..cc09dca 100644 > --- a/kernel/printk.c > +++ b/kernel/printk.c > @@ -602,6 +602,30 @@ out: > EXPORT_SYMBOL(printk); > EXPORT_SYMBOL(vprintk); > > +#ifdef CONFIG_DEBUG_LIKELY > +int debug_likely_count_min_thresh = 100; > +int debug_likely_print_max_thresh = 1; > +int printk_debug_likely(const char *fmt, ...) > +{ > + int r = 0; > + static atomic_t recurse = ATOMIC_INIT(1); /* as a mutex */ > + if (atomic_dec_and_test(&recurse)) { > + va_list args; > + > + va_start(args, fmt); > + r = vprintk(fmt, args); > + va_end(args); > + dump_stack(); > + } > + atomic_inc(&recurse); > + > + return r; > +} > +EXPORT_SYMBOL(debug_likely_count_min_thresh); > +EXPORT_SYMBOL(debug_likely_print_max_thresh); > +EXPORT_SYMBOL(printk_debug_likely); > +#endif > + > #else > > asmlinkage long sys_syslog(int type, char __user *buf, int len) > >
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