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author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-05-09 13:07:03 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-05-09 13:07:03 -0700 |
commit | 732a27a0891cb5db1a0f9c33a018ea6eca9a4023 (patch) | |
tree | 35d7ee5c21df90cb66c6734e11a777f1be3df66d | |
parent | 85bbba1c077848e76ab77682e9e56c41113f5770 (diff) | |
parent | 51cf94d16860a324e97d1b670d88f1f2b643bc32 (diff) | |
download | lwn-732a27a0891cb5db1a0f9c33a018ea6eca9a4023.tar.gz lwn-732a27a0891cb5db1a0f9c33a018ea6eca9a4023.zip |
Merge tag 'locking-urgent-2021-05-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Thomas Gleixner:
"A set of locking related fixes and updates:
- Two fixes for the futex syscall related to the timeout handling.
FUTEX_LOCK_PI does not support the FUTEX_CLOCK_REALTIME bit and
because it's not set the time namespace adjustment for clock
MONOTONIC is applied wrongly.
FUTEX_WAIT cannot support the FUTEX_CLOCK_REALTIME bit because its
always a relative timeout.
- Cleanups in the futex syscall entry points which became obvious
when the two timeout handling bugs were fixed.
- Cleanup of queued_write_lock_slowpath() as suggested by Linus
- Fixup of the smp_call_function_single_async() prototype"
* tag 'locking-urgent-2021-05-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
futex: Make syscall entry points less convoluted
futex: Get rid of the val2 conditional dance
futex: Do not apply time namespace adjustment on FUTEX_LOCK_PI
Revert 337f13046ff0 ("futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op")
locking/qrwlock: Cleanup queued_write_lock_slowpath()
smp: Fix smp_call_function_single_async prototype
-rw-r--r-- | include/linux/smp.h | 2 | ||||
-rw-r--r-- | kernel/futex.c | 82 | ||||
-rw-r--r-- | kernel/locking/qrwlock.c | 6 | ||||
-rw-r--r-- | kernel/smp.c | 26 | ||||
-rw-r--r-- | kernel/up.c | 2 |
5 files changed, 58 insertions, 60 deletions
diff --git a/include/linux/smp.h b/include/linux/smp.h index 669e35c03be2..510519e8a1eb 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -53,7 +53,7 @@ int smp_call_function_single(int cpuid, smp_call_func_t func, void *info, void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func, void *info, bool wait, const struct cpumask *mask); -int smp_call_function_single_async(int cpu, call_single_data_t *csd); +int smp_call_function_single_async(int cpu, struct __call_single_data *csd); /* * Cpus stopping functions in panic. All have default weak definitions. diff --git a/kernel/futex.c b/kernel/futex.c index c98b825da9cf..4938a00bc785 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -3710,8 +3710,7 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, if (op & FUTEX_CLOCK_REALTIME) { flags |= FLAGS_CLOCKRT; - if (cmd != FUTEX_WAIT && cmd != FUTEX_WAIT_BITSET && \ - cmd != FUTEX_WAIT_REQUEUE_PI) + if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI) return -ENOSYS; } @@ -3758,42 +3757,52 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, return -ENOSYS; } +static __always_inline bool futex_cmd_has_timeout(u32 cmd) +{ + switch (cmd) { + case FUTEX_WAIT: + case FUTEX_LOCK_PI: + case FUTEX_WAIT_BITSET: + case FUTEX_WAIT_REQUEUE_PI: + return true; + } + return false; +} + +static __always_inline int +futex_init_timeout(u32 cmd, u32 op, struct timespec64 *ts, ktime_t *t) +{ + if (!timespec64_valid(ts)) + return -EINVAL; + + *t = timespec64_to_ktime(*ts); + if (cmd == FUTEX_WAIT) + *t = ktime_add_safe(ktime_get(), *t); + else if (cmd != FUTEX_LOCK_PI && !(op & FUTEX_CLOCK_REALTIME)) + *t = timens_ktime_to_host(CLOCK_MONOTONIC, *t); + return 0; +} SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, const struct __kernel_timespec __user *, utime, u32 __user *, uaddr2, u32, val3) { - struct timespec64 ts; + int ret, cmd = op & FUTEX_CMD_MASK; ktime_t t, *tp = NULL; - u32 val2 = 0; - int cmd = op & FUTEX_CMD_MASK; + struct timespec64 ts; - if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || - cmd == FUTEX_WAIT_BITSET || - cmd == FUTEX_WAIT_REQUEUE_PI)) { + if (utime && futex_cmd_has_timeout(cmd)) { if (unlikely(should_fail_futex(!(op & FUTEX_PRIVATE_FLAG)))) return -EFAULT; if (get_timespec64(&ts, utime)) return -EFAULT; - if (!timespec64_valid(&ts)) - return -EINVAL; - - t = timespec64_to_ktime(ts); - if (cmd == FUTEX_WAIT) - t = ktime_add_safe(ktime_get(), t); - else if (!(op & FUTEX_CLOCK_REALTIME)) - t = timens_ktime_to_host(CLOCK_MONOTONIC, t); + ret = futex_init_timeout(cmd, op, &ts, &t); + if (ret) + return ret; tp = &t; } - /* - * requeue parameter in 'utime' if cmd == FUTEX_*_REQUEUE_*. - * number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP. - */ - if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || - cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP) - val2 = (u32) (unsigned long) utime; - return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); + return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3); } #ifdef CONFIG_COMPAT @@ -3959,31 +3968,20 @@ SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val, const struct old_timespec32 __user *, utime, u32 __user *, uaddr2, u32, val3) { - struct timespec64 ts; + int ret, cmd = op & FUTEX_CMD_MASK; ktime_t t, *tp = NULL; - int val2 = 0; - int cmd = op & FUTEX_CMD_MASK; + struct timespec64 ts; - if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || - cmd == FUTEX_WAIT_BITSET || - cmd == FUTEX_WAIT_REQUEUE_PI)) { + if (utime && futex_cmd_has_timeout(cmd)) { if (get_old_timespec32(&ts, utime)) return -EFAULT; - if (!timespec64_valid(&ts)) - return -EINVAL; - - t = timespec64_to_ktime(ts); - if (cmd == FUTEX_WAIT) - t = ktime_add_safe(ktime_get(), t); - else if (!(op & FUTEX_CLOCK_REALTIME)) - t = timens_ktime_to_host(CLOCK_MONOTONIC, t); + ret = futex_init_timeout(cmd, op, &ts, &t); + if (ret) + return ret; tp = &t; } - if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || - cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP) - val2 = (int) (unsigned long) utime; - return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); + return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3); } #endif /* CONFIG_COMPAT_32BIT_TIME */ diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c index b94f3831e963..ec36b73f4733 100644 --- a/kernel/locking/qrwlock.c +++ b/kernel/locking/qrwlock.c @@ -66,12 +66,12 @@ void queued_write_lock_slowpath(struct qrwlock *lock) arch_spin_lock(&lock->wait_lock); /* Try to acquire the lock directly if no reader is present */ - if (!atomic_read(&lock->cnts) && - (atomic_cmpxchg_acquire(&lock->cnts, 0, _QW_LOCKED) == 0)) + if (!(cnts = atomic_read(&lock->cnts)) && + atomic_try_cmpxchg_acquire(&lock->cnts, &cnts, _QW_LOCKED)) goto unlock; /* Set the waiting flag to notify readers that a writer is pending */ - atomic_add(_QW_WAITING, &lock->cnts); + atomic_or(_QW_WAITING, &lock->cnts); /* When no more readers or writers, set the locked flag */ do { diff --git a/kernel/smp.c b/kernel/smp.c index e21074900006..52bf159ec400 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -211,7 +211,7 @@ static u64 cfd_seq_inc(unsigned int src, unsigned int dst, unsigned int type) } while (0) /* Record current CSD work for current CPU, NULL to erase. */ -static void __csd_lock_record(call_single_data_t *csd) +static void __csd_lock_record(struct __call_single_data *csd) { if (!csd) { smp_mb(); /* NULL cur_csd after unlock. */ @@ -226,13 +226,13 @@ static void __csd_lock_record(call_single_data_t *csd) /* Or before unlock, as the case may be. */ } -static __always_inline void csd_lock_record(call_single_data_t *csd) +static __always_inline void csd_lock_record(struct __call_single_data *csd) { if (static_branch_unlikely(&csdlock_debug_enabled)) __csd_lock_record(csd); } -static int csd_lock_wait_getcpu(call_single_data_t *csd) +static int csd_lock_wait_getcpu(struct __call_single_data *csd) { unsigned int csd_type; @@ -282,7 +282,7 @@ static const char *csd_lock_get_type(unsigned int type) return (type >= ARRAY_SIZE(seq_type)) ? "?" : seq_type[type]; } -static void csd_lock_print_extended(call_single_data_t *csd, int cpu) +static void csd_lock_print_extended(struct __call_single_data *csd, int cpu) { struct cfd_seq_local *seq = &per_cpu(cfd_seq_local, cpu); unsigned int srccpu = csd->node.src; @@ -321,7 +321,7 @@ static void csd_lock_print_extended(call_single_data_t *csd, int cpu) * the CSD_TYPE_SYNC/ASYNC types provide the destination CPU, * so waiting on other types gets much less information. */ -static bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id) +static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 *ts1, int *bug_id) { int cpu = -1; int cpux; @@ -387,7 +387,7 @@ static bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, in * previous function call. For multi-cpu calls its even more interesting * as we'll have to ensure no other cpu is observing our csd. */ -static void __csd_lock_wait(call_single_data_t *csd) +static void __csd_lock_wait(struct __call_single_data *csd) { int bug_id = 0; u64 ts0, ts1; @@ -401,7 +401,7 @@ static void __csd_lock_wait(call_single_data_t *csd) smp_acquire__after_ctrl_dep(); } -static __always_inline void csd_lock_wait(call_single_data_t *csd) +static __always_inline void csd_lock_wait(struct __call_single_data *csd) { if (static_branch_unlikely(&csdlock_debug_enabled)) { __csd_lock_wait(csd); @@ -431,17 +431,17 @@ static void __smp_call_single_queue_debug(int cpu, struct llist_node *node) #else #define cfd_seq_store(var, src, dst, type) -static void csd_lock_record(call_single_data_t *csd) +static void csd_lock_record(struct __call_single_data *csd) { } -static __always_inline void csd_lock_wait(call_single_data_t *csd) +static __always_inline void csd_lock_wait(struct __call_single_data *csd) { smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK)); } #endif -static __always_inline void csd_lock(call_single_data_t *csd) +static __always_inline void csd_lock(struct __call_single_data *csd) { csd_lock_wait(csd); csd->node.u_flags |= CSD_FLAG_LOCK; @@ -454,7 +454,7 @@ static __always_inline void csd_lock(call_single_data_t *csd) smp_wmb(); } -static __always_inline void csd_unlock(call_single_data_t *csd) +static __always_inline void csd_unlock(struct __call_single_data *csd) { WARN_ON(!(csd->node.u_flags & CSD_FLAG_LOCK)); @@ -501,7 +501,7 @@ void __smp_call_single_queue(int cpu, struct llist_node *node) * for execution on the given CPU. data must already have * ->func, ->info, and ->flags set. */ -static int generic_exec_single(int cpu, call_single_data_t *csd) +static int generic_exec_single(int cpu, struct __call_single_data *csd) { if (cpu == smp_processor_id()) { smp_call_func_t func = csd->func; @@ -784,7 +784,7 @@ EXPORT_SYMBOL(smp_call_function_single); * NOTE: Be careful, there is unfortunately no current debugging facility to * validate the correctness of this serialization. */ -int smp_call_function_single_async(int cpu, call_single_data_t *csd) +int smp_call_function_single_async(int cpu, struct __call_single_data *csd) { int err = 0; diff --git a/kernel/up.c b/kernel/up.c index df50828cc2f0..a38b8b095251 100644 --- a/kernel/up.c +++ b/kernel/up.c @@ -25,7 +25,7 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info, } EXPORT_SYMBOL(smp_call_function_single); -int smp_call_function_single_async(int cpu, call_single_data_t *csd) +int smp_call_function_single_async(int cpu, struct __call_single_data *csd) { unsigned long flags; |