Jens wrote:
>On Mon, Jan 13 2003, Terje Eggestad wrote:
>> > > I have the console on a serial port, and a terminal server. With kdb,
>> > > you can enter the kernel i kdb even when deadlocked.
>> >
>> > Even if spinning with interrupt disabled?
>>
>> Haven't painted myself into that corner yet. Doubt it, very much.
>
>These are the nasty hangs, total lockup and no info at all if it wasn't
>for the nmi watchdog triggering. That alone is reason enough for me :-)
>
>
One alternative are the UP debug spinlocks: They detect double-locks.
2.4 contains macros, but I'm not sure if they work.
The macros were removed in 2.5, but if anyone is interested, I've
attached my debug spinlock patch: for double locks, it even prints the
filename/lineno of the offender.
--
Manfred
--- 2.5/include/linux/spinlock.h 2002-12-14 10:06:57.000000000 +0100 +++ build-2.5/include/linux/spinlock.h 2002-12-21 14:36:42.000000000 +0100 @@ -37,30 +37,120 @@ #ifdef CONFIG_SMP #include <asm/spinlock.h> -/* - * !CONFIG_SMP and spin_lock_init not previously defined - * (e.g. by including include/asm/spinlock.h) - */ -#elif !defined(spin_lock_init) +#else -#ifndef CONFIG_PREEMPT +#if !defined(CONFIG_PREEMPT) && !defined(CONFIG_DEBUG_SPINLOCK) # define atomic_dec_and_lock(atomic,lock) atomic_dec_and_test(atomic) # define ATOMIC_DEC_AND_LOCK #endif +#ifdef CONFIG_DEBUG_SPINLOCK + +#define SPINLOCK_MAGIC 0x1D244B3C +typedef struct { + unsigned long magic; + volatile unsigned long lock; + volatile unsigned int babble; + const char *module; + char *owner; + int oline; +} spinlock_t; +#define SPIN_LOCK_UNLOCKED (spinlock_t) { SPINLOCK_MAGIC, 0, 10, __FILE__ , NULL, 0} + +#define spin_lock_init(x) \ + do { \ + (x)->magic = SPINLOCK_MAGIC; \ + (x)->lock = 0; \ + (x)->babble = 5; \ + (x)->module = __FILE__; \ + (x)->owner = NULL; \ + (x)->oline = 0; \ + } while (0) + +#define CHECK_LOCK(x) \ + do { \ + if ((x)->magic != SPINLOCK_MAGIC) { \ + printk(KERN_ERR "%s:%d: spin_is_locked on uninitialized spinlock %p.\n", \ + __FILE__, __LINE__, (x)); \ + } \ + } while(0) + +#define _raw_spin_lock(x) \ + do { \ + CHECK_LOCK(x); \ + if ((x)->lock&&(x)->babble) { \ + printk("%s:%d: spin_lock(%s:%p) already locked by %s/%d\n", \ + __FILE__,__LINE__, (x)->module, \ + (x), (x)->owner, (x)->oline); \ + (x)->babble--; \ + } \ + (x)->lock = 1; \ + (x)->owner = __FILE__; \ + (x)->oline = __LINE__; \ + } while (0) + +/* without debugging, spin_is_locked on UP always says + * FALSE. --> printk if already locked. */ +#define spin_is_locked(x) \ + ({ \ + CHECK_LOCK(x); \ + if ((x)->lock&&(x)->babble) { \ + printk("%s:%d: spin_is_locked(%s:%p) already locked by %s/%d\n", \ + __FILE__,__LINE__, (x)->module, \ + (x), (x)->owner, (x)->oline); \ + (x)->babble--; \ + } \ + 0; \ + }) + +/* without debugging, spin_trylock on UP always says + * TRUE. --> printk if already locked. */ +#define _raw_spin_trylock(x) \ + ({ \ + CHECK_LOCK(x); \ + if ((x)->lock&&(x)->babble) { \ + printk("%s:%d: spin_trylock(%s:%p) already locked by %s/%d\n", \ + __FILE__,__LINE__, (x)->module, \ + (x), (x)->owner, (x)->oline); \ + (x)->babble--; \ + } \ + (x)->lock = 1; \ + (x)->owner = __FILE__; \ + (x)->oline = __LINE__; \ + 1; \ + }) + +#define spin_unlock_wait(x) \ + do { \ + CHECK_LOCK(x); \ + if ((x)->lock&&(x)->babble) { \ + printk("%s:%d: spin_unlock_wait(%s:%p) owned by %s/%d\n", \ + __FILE__,__LINE__, (x)->module, (x), \ + (x)->owner, (x)->oline); \ + (x)->babble--; \ + }\ + } while (0) + +#define _raw_spin_unlock(x) \ + do { \ + CHECK_LOCK(x); \ + if (!(x)->lock&&(x)->babble) { \ + printk("%s:%d: spin_unlock(%s:%p) not locked\n", \ + __FILE__,__LINE__, (x)->module, (x));\ + (x)->babble--; \ + } \ + (x)->lock = 0; \ + } while (0) +#else /* * gcc versions before ~2.95 have a nasty bug with empty initializers. */ #if (__GNUC__ > 2) typedef struct { } spinlock_t; - typedef struct { } rwlock_t; #define SPIN_LOCK_UNLOCKED (spinlock_t) { } - #define RW_LOCK_UNLOCKED (rwlock_t) { } #else typedef struct { int gcc_is_buggy; } spinlock_t; - typedef struct { int gcc_is_buggy; } rwlock_t; #define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 } - #define RW_LOCK_UNLOCKED (rwlock_t) { 0 } #endif /* @@ -72,6 +162,18 @@ #define _raw_spin_trylock(lock) ((void)(lock), 1) #define spin_unlock_wait(lock) do { (void)(lock); } while(0) #define _raw_spin_unlock(lock) do { (void)(lock); } while(0) +#endif /* CONFIG_DEBUG_SPINLOCK */ + +/* RW spinlocks: No debug version */ + +#if (__GNUC__ > 2) + typedef struct { } rwlock_t; + #define RW_LOCK_UNLOCKED (rwlock_t) { } +#else + typedef struct { int gcc_is_buggy; } rwlock_t; + #define RW_LOCK_UNLOCKED (rwlock_t) { 0 } +#endif + #define rwlock_init(lock) do { (void)(lock); } while(0) #define _raw_read_lock(lock) do { (void)(lock); } while(0) #define _raw_read_unlock(lock) do { (void)(lock); } while(0)
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This archive was generated by hypermail 2b29 : Wed Jan 15 2003 - 22:00:47 EST