by Waiman Long

[permalink] [raw]

Subject: Re: [PATCH v2 bpf-next 03/13] Revert "locking/spinlocks: Remove the unused spin_lock_bh_nested() API"

On 12/7/20 8:24 AM, Kuniyuki Iwashima wrote:
> This reverts commit 607904c357c61adf20b8fd18af765e501d61a385 to use
> spin_lock_bh_nested() in the next commit.
>
> Link: https://lore.kernel.org/netdev/[email protected]/
> Signed-off-by: Kuniyuki Iwashima <[email protected]>
> CC: Waiman Long <[email protected]>

If there is a use case for spin_lock_bh_nested(), it is perfectly fine
to add it back.

Acked-by: Waiman Long <[email protected]>

> ---
> include/linux/spinlock.h | 8 ++++++++
> include/linux/spinlock_api_smp.h | 2 ++
> include/linux/spinlock_api_up.h | 1 +
> kernel/locking/spinlock.c | 8 ++++++++
> 4 files changed, 19 insertions(+)
>
> diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
> index 79897841a2cc..c020b375a071 100644
> --- a/include/linux/spinlock.h
> +++ b/include/linux/spinlock.h
> @@ -227,6 +227,8 @@ static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
> #ifdef CONFIG_DEBUG_LOCK_ALLOC
> # define raw_spin_lock_nested(lock, subclass) \
> _raw_spin_lock_nested(lock, subclass)
> +# define raw_spin_lock_bh_nested(lock, subclass) \
> + _raw_spin_lock_bh_nested(lock, subclass)
>
> # define raw_spin_lock_nest_lock(lock, nest_lock) \
> do { \
> @@ -242,6 +244,7 @@ static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
> # define raw_spin_lock_nested(lock, subclass) \
> _raw_spin_lock(((void)(subclass), (lock)))
> # define raw_spin_lock_nest_lock(lock, nest_lock) _raw_spin_lock(lock)
> +# define raw_spin_lock_bh_nested(lock, subclass) _raw_spin_lock_bh(lock)
> #endif
>
> #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
> @@ -369,6 +372,11 @@ do { \
> raw_spin_lock_nested(spinlock_check(lock), subclass); \
> } while (0)
>
> +#define spin_lock_bh_nested(lock, subclass) \
> +do { \
> + raw_spin_lock_bh_nested(spinlock_check(lock), subclass);\
> +} while (0)
> +
> #define spin_lock_nest_lock(lock, nest_lock) \
> do { \
> raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock); \
> diff --git a/include/linux/spinlock_api_smp.h b/include/linux/spinlock_api_smp.h
> index 19a9be9d97ee..d565fb6304f2 100644
> --- a/include/linux/spinlock_api_smp.h
> +++ b/include/linux/spinlock_api_smp.h
> @@ -22,6 +22,8 @@ int in_lock_functions(unsigned long addr);
> void __lockfunc _raw_spin_lock(raw_spinlock_t *lock) __acquires(lock);
> void __lockfunc _raw_spin_lock_nested(raw_spinlock_t *lock, int subclass)
> __acquires(lock);
> +void __lockfunc _raw_spin_lock_bh_nested(raw_spinlock_t *lock, int subclass)
> + __acquires(lock);
> void __lockfunc
> _raw_spin_lock_nest_lock(raw_spinlock_t *lock, struct lockdep_map *map)
> __acquires(lock);
> diff --git a/include/linux/spinlock_api_up.h b/include/linux/spinlock_api_up.h
> index d0d188861ad6..d3afef9d8dbe 100644
> --- a/include/linux/spinlock_api_up.h
> +++ b/include/linux/spinlock_api_up.h
> @@ -57,6 +57,7 @@
>
> #define _raw_spin_lock(lock) __LOCK(lock)
> #define _raw_spin_lock_nested(lock, subclass) __LOCK(lock)
> +#define _raw_spin_lock_bh_nested(lock, subclass) __LOCK(lock)
> #define _raw_read_lock(lock) __LOCK(lock)
> #define _raw_write_lock(lock) __LOCK(lock)
> #define _raw_spin_lock_bh(lock) __LOCK_BH(lock)
> diff --git a/kernel/locking/spinlock.c b/kernel/locking/spinlock.c
> index 0ff08380f531..48e99ed1bdd8 100644
> --- a/kernel/locking/spinlock.c
> +++ b/kernel/locking/spinlock.c
> @@ -363,6 +363,14 @@ void __lockfunc _raw_spin_lock_nested(raw_spinlock_t *lock, int subclass)
> }
> EXPORT_SYMBOL(_raw_spin_lock_nested);
>
> +void __lockfunc _raw_spin_lock_bh_nested(raw_spinlock_t *lock, int subclass)
> +{
> + __local_bh_disable_ip(_RET_IP_, SOFTIRQ_LOCK_OFFSET);
> + spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
> + LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
> +}
> +EXPORT_SYMBOL(_raw_spin_lock_bh_nested);
> +
> unsigned long __lockfunc _raw_spin_lock_irqsave_nested(raw_spinlock_t *lock,
> int subclass)
> {