any chance of 2.6.0-test*?
Quoted 4 lines · Jens
Quoted 3 lines · Terje Eggestad
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I have the console on a serial port, and a terminal server. With kdb, you can enter the kernel i kdb even when deadlocked.
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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
include/linux/spinlock.h +112 -10
@@ -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)