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rwlock_reader_lock: fix lock list jammed up

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This commit is contained in:
Tomoki Shirasawa
2016-03-03 22:47:48 +09:00
parent 8ebb3a4231
commit 26c0180374
2 changed files with 44 additions and 31 deletions
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62
arch/x86/kernel/include/arch-lock.h
View File

@@ -13,7 +13,6 @@
#if defined(DEBUG_SPINLOCK) || defined(DEBUG_MCS_RWLOCK) #if defined(DEBUG_SPINLOCK) || defined(DEBUG_MCS_RWLOCK)
int __kprintf(const char *format, ...); int __kprintf(const char *format, ...);
#endif #endif
extern void panic(const char *);
typedef int ihk_spinlock_t; typedef int ihk_spinlock_t;
@@ -189,10 +188,8 @@ typedef struct mcs_rwlock_node {
char locked; // lock char locked; // lock
#define MCS_RWLOCK_LOCKED 1 #define MCS_RWLOCK_LOCKED 1
#define MCS_RWLOCK_UNLOCKED 0 #define MCS_RWLOCK_UNLOCKED 0
char status;
#define MCS_RWLOCK_STAT_INACTIVE 0
#define MCS_RWLOCK_STAT_INPROGRESS 1
char dmy1; // unused char dmy1; // unused
char dmy2; // unused
struct mcs_rwlock_node *next; struct mcs_rwlock_node *next;
} __attribute__((aligned(64))) mcs_rwlock_node_t; } __attribute__((aligned(64))) mcs_rwlock_node_t;
@@ -211,7 +208,6 @@ mcs_rwlock_init(struct mcs_rwlock_lock *lock)
{ {
ihk_atomic_set(&lock->reader.count, 0); ihk_atomic_set(&lock->reader.count, 0);
lock->reader.type = MCS_RWLOCK_TYPE_COMMON_READER; lock->reader.type = MCS_RWLOCK_TYPE_COMMON_READER;
lock->reader.status = MCS_RWLOCK_STAT_INACTIVE;
lock->node = NULL; lock->node = NULL;
} }
@@ -252,11 +248,12 @@ mcs_rwlock_unlock_readers(struct mcs_rwlock_lock *lock)
struct mcs_rwlock_node *p; struct mcs_rwlock_node *p;
struct mcs_rwlock_node *f = NULL; struct mcs_rwlock_node *f = NULL;
struct mcs_rwlock_node *n; struct mcs_rwlock_node *n;
int breakf = 0;
ihk_atomic_inc(&lock->reader.count); // protect to unlock reader ihk_atomic_inc(&lock->reader.count); // protect to unlock reader
for(p = &lock->reader; p->next; p = n){ for(p = &lock->reader; p->next; p = n){
n = p->next; n = p->next;
if(n->type == MCS_RWLOCK_TYPE_READER){ if(p->next->type == MCS_RWLOCK_TYPE_READER){
p->next = n->next; p->next = n->next;
if(lock->node == n){ if(lock->node == n){
struct mcs_rwlock_node *old; struct mcs_rwlock_node *old;
@@ -272,6 +269,9 @@ mcs_rwlock_unlock_readers(struct mcs_rwlock_lock *lock)
} }
p->next = n->next; p->next = n->next;
} }
else{
breakf = 1;
}
} }
else if(p->next == NULL){ else if(p->next == NULL){
while (n->next == NULL) { while (n->next == NULL) {
@@ -286,6 +286,8 @@ mcs_rwlock_unlock_readers(struct mcs_rwlock_lock *lock)
else else
f = n; f = n;
n = p; n = p;
if(breakf)
break;
} }
if(n->next == NULL && lock->node != n){ if(n->next == NULL && lock->node != n){
while (n->next == NULL && lock->node != n) { while (n->next == NULL && lock->node != n) {
@@ -294,7 +296,6 @@ mcs_rwlock_unlock_readers(struct mcs_rwlock_lock *lock)
} }
} }
lock->reader.status = MCS_RWLOCK_STAT_INACTIVE;
f->locked = MCS_RWLOCK_UNLOCKED; f->locked = MCS_RWLOCK_UNLOCKED;
} }
@@ -325,10 +326,6 @@ __mcs_rwlock_writer_unlock_noirq(struct mcs_rwlock_lock *lock, struct mcs_rwlock
} }
if(node->next->type == MCS_RWLOCK_TYPE_READER){ if(node->next->type == MCS_RWLOCK_TYPE_READER){
if(lock->reader.status == MCS_RWLOCK_STAT_INPROGRESS){
panic("panic __mcs_rwlock_writer_unlock_noirq\n");
}
lock->reader.status = MCS_RWLOCK_STAT_INPROGRESS;
lock->reader.next = node->next; lock->reader.next = node->next;
mcs_rwlock_unlock_readers(lock); mcs_rwlock_unlock_readers(lock);
} }
@@ -349,6 +346,24 @@ __kprintf("[%d] ret mcs_rwlock_reader_lock_noirq\n", ihk_mc_get_processor_id());
#else #else
#define mcs_rwlock_reader_lock_noirq __mcs_rwlock_reader_lock_noirq #define mcs_rwlock_reader_lock_noirq __mcs_rwlock_reader_lock_noirq
#endif #endif
static inline unsigned int
atomic_inc_ifnot0(ihk_atomic_t *v)
{
unsigned int *p = (unsigned int *)(&(v)->counter);
unsigned int old;
unsigned int new;
unsigned int val;
do{
if(!(old = *p))
break;
new = old + 1;
val = atomic_cmpxchg4(p, old, new);
}while(val != old);
return old;
}
static void static void
__mcs_rwlock_reader_lock_noirq(struct mcs_rwlock_lock *lock, struct mcs_rwlock_node *node) __mcs_rwlock_reader_lock_noirq(struct mcs_rwlock_lock *lock, struct mcs_rwlock_node *node)
{ {
@@ -356,8 +371,6 @@ __mcs_rwlock_reader_lock_noirq(struct mcs_rwlock_lock *lock, struct mcs_rwlock_n
preempt_disable(); preempt_disable();
while(lock->reader.status != MCS_RWLOCK_STAT_INACTIVE)
cpu_pause();
node->type = MCS_RWLOCK_TYPE_READER; node->type = MCS_RWLOCK_TYPE_READER;
node->next = NULL; node->next = NULL;
node->dmy1 = ihk_mc_get_processor_id(); node->dmy1 = ihk_mc_get_processor_id();
@@ -367,7 +380,7 @@ __mcs_rwlock_reader_lock_noirq(struct mcs_rwlock_lock *lock, struct mcs_rwlock_n
if (pred) { if (pred) {
if(pred == &lock->reader){ if(pred == &lock->reader){
if(ihk_atomic_inc_return(&pred->count) != 1){ if(atomic_inc_ifnot0(&pred->count)){
struct mcs_rwlock_node *old; struct mcs_rwlock_node *old;
old = (struct mcs_rwlock_node *)atomic_cmpxchg8( old = (struct mcs_rwlock_node *)atomic_cmpxchg8(
@@ -383,17 +396,12 @@ __mcs_rwlock_reader_lock_noirq(struct mcs_rwlock_lock *lock, struct mcs_rwlock_n
cpu_pause(); cpu_pause();
} }
pred->next = node->next; node->locked = MCS_RWLOCK_LOCKED;
if(node->next->type == MCS_RWLOCK_TYPE_READER){ lock->reader.next = node;
if(lock->reader.status == MCS_RWLOCK_STAT_INPROGRESS){ mcs_rwlock_unlock_readers(lock);
panic("panic __mcs_rwlock_reader_lock_noirq 1\n"); ihk_atomic_dec(&pred->count);
}
lock->reader.status = MCS_RWLOCK_STAT_INPROGRESS;
mcs_rwlock_unlock_readers(lock);
}
goto out; goto out;
} }
ihk_atomic_dec(&pred->count);
} }
node->locked = MCS_RWLOCK_LOCKED; node->locked = MCS_RWLOCK_LOCKED;
pred->next = node; pred->next = node;
@@ -402,10 +410,6 @@ panic("panic __mcs_rwlock_reader_lock_noirq 1\n");
} }
} }
else { else {
if(lock->reader.status == MCS_RWLOCK_STAT_INPROGRESS){
panic("panic __mcs_rwlock_reader_lock_noirq 2\n");
}
lock->reader.status = MCS_RWLOCK_STAT_INPROGRESS;
lock->reader.next = node; lock->reader.next = node;
mcs_rwlock_unlock_readers(lock); mcs_rwlock_unlock_readers(lock);
} }
@@ -446,10 +450,6 @@ __mcs_rwlock_reader_unlock_noirq(struct mcs_rwlock_lock *lock, struct mcs_rwlock
} }
if(lock->reader.next->type == MCS_RWLOCK_TYPE_READER){ if(lock->reader.next->type == MCS_RWLOCK_TYPE_READER){
if(lock->reader.status == MCS_RWLOCK_STAT_INPROGRESS){
panic("panic __mcs_rwlock_reader_unlock_noirq\n");
}
lock->reader.status = MCS_RWLOCK_STAT_INPROGRESS;
mcs_rwlock_unlock_readers(lock); mcs_rwlock_unlock_readers(lock);
} }
else{ else{

13
arch/x86/kernel/include/ihk/atomic.h
View File

@@ -202,4 +202,17 @@ static inline unsigned long atomic_cmpxchg8(unsigned long *addr,
return oldval; return oldval;
} }
static inline unsigned long atomic_cmpxchg4(unsigned int *addr,
unsigned int oldval,
unsigned int newval)
{
asm volatile("lock; cmpxchgl %2, %1\n"
: "=a" (oldval), "+m" (*addr)
: "r" (newval), "0" (oldval)
: "memory"
);
return oldval;
}
#endif #endif