Messages in this thread Patch in this message | | | From | Guo Ren <> | Date | Thu, 31 Aug 2023 14:58:08 +0800 | Subject | Re: [RFC PATCH 1/1] smp: Change function signatures to use call_single_data_t |
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On Thu, Aug 31, 2023 at 2:31 PM Leonardo Bras <leobras@redhat.com> wrote: > > call_single_data_t is a size-aligned typedef of struct __call_single_data. > > This alignment is desirable in order to have smp_call_function*() avoid > bouncing an extra cacheline in case of an unaligned csd, given this > would hurt performance. > > Since the removal of struct request->csd in commit 660e802c76c8 > ("blk-mq: use percpu csd to remote complete instead of per-rq csd") there > are no current users of smp_call_function*() with unaligned csd. > > Change every 'struct __call_single_data' function parameter to > 'call_single_data_t', so we have warnings if any new code tries to > introduce an smp_call_function*() call with unaligned csd. I agree to prevent __call_single_data usage.
Reviewed-by: Guo Ren <guoren@kernel.org>
/* * structure shares (partial) layout with struct irq_work */ struct __call_single_data { struct __call_single_node node; smp_call_func_t func; void *info; };
#define CSD_INIT(_func, _info) \ (struct __call_single_data){ .func = (_func), .info = (_info), }
/* Use __aligned() to avoid to use 2 cache lines for 1 csd */ typedef struct __call_single_data call_single_data_t __aligned(sizeof(struct __call_single_data));
> > Signed-off-by: Leonardo Bras <leobras@redhat.com> > --- > include/linux/smp.h | 2 +- > include/trace/events/csd.h | 8 ++++---- > kernel/smp.c | 26 +++++++++++++------------- > kernel/up.c | 2 +- > 4 files changed, 19 insertions(+), 19 deletions(-) > > diff --git a/include/linux/smp.h b/include/linux/smp.h > index 91ea4a67f8ca..e87520dc2959 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, struct __call_single_data *csd); > +int smp_call_function_single_async(int cpu, call_single_data_t *csd); > > /* > * Cpus stopping functions in panic. All have default weak definitions. > diff --git a/include/trace/events/csd.h b/include/trace/events/csd.h > index 67e9d01f80c2..58cc83b99c34 100644 > --- a/include/trace/events/csd.h > +++ b/include/trace/events/csd.h > @@ -12,7 +12,7 @@ TRACE_EVENT(csd_queue_cpu, > TP_PROTO(const unsigned int cpu, > unsigned long callsite, > smp_call_func_t func, > - struct __call_single_data *csd), > + call_single_data_t *csd), > > TP_ARGS(cpu, callsite, func, csd), > > @@ -39,7 +39,7 @@ TRACE_EVENT(csd_queue_cpu, > */ > DECLARE_EVENT_CLASS(csd_function, > > - TP_PROTO(smp_call_func_t func, struct __call_single_data *csd), > + TP_PROTO(smp_call_func_t func, call_single_data_t *csd), > > TP_ARGS(func, csd), > > @@ -57,12 +57,12 @@ DECLARE_EVENT_CLASS(csd_function, > ); > > DEFINE_EVENT(csd_function, csd_function_entry, > - TP_PROTO(smp_call_func_t func, struct __call_single_data *csd), > + TP_PROTO(smp_call_func_t func, call_single_data_t *csd), > TP_ARGS(func, csd) > ); > > DEFINE_EVENT(csd_function, csd_function_exit, > - TP_PROTO(smp_call_func_t func, struct __call_single_data *csd), > + TP_PROTO(smp_call_func_t func, call_single_data_t *csd), > TP_ARGS(func, csd) > ); > > diff --git a/kernel/smp.c b/kernel/smp.c > index 8455a53465af..8c714583786b 100644 > --- a/kernel/smp.c > +++ b/kernel/smp.c > @@ -127,7 +127,7 @@ send_call_function_ipi_mask(struct cpumask *mask) > } > > static __always_inline void > -csd_do_func(smp_call_func_t func, void *info, struct __call_single_data *csd) > +csd_do_func(smp_call_func_t func, void *info, call_single_data_t *csd) > { > trace_csd_function_entry(func, csd); > func(info); > @@ -174,7 +174,7 @@ module_param(csd_lock_timeout, ulong, 0444); > static atomic_t csd_bug_count = ATOMIC_INIT(0); > > /* Record current CSD work for current CPU, NULL to erase. */ > -static void __csd_lock_record(struct __call_single_data *csd) > +static void __csd_lock_record(call_single_data_t *csd) > { > if (!csd) { > smp_mb(); /* NULL cur_csd after unlock. */ > @@ -189,13 +189,13 @@ static void __csd_lock_record(struct __call_single_data *csd) > /* Or before unlock, as the case may be. */ > } > > -static __always_inline void csd_lock_record(struct __call_single_data *csd) > +static __always_inline void csd_lock_record(call_single_data_t *csd) > { > if (static_branch_unlikely(&csdlock_debug_enabled)) > __csd_lock_record(csd); > } > > -static int csd_lock_wait_getcpu(struct __call_single_data *csd) > +static int csd_lock_wait_getcpu(call_single_data_t *csd) > { > unsigned int csd_type; > > @@ -210,7 +210,7 @@ static int csd_lock_wait_getcpu(struct __call_single_data *csd) > * 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(struct __call_single_data *csd, u64 ts0, u64 *ts1, int *bug_id) > +static bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id) > { > int cpu = -1; > int cpux; > @@ -276,7 +276,7 @@ static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 * > * 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(struct __call_single_data *csd) > +static void __csd_lock_wait(call_single_data_t *csd) > { > int bug_id = 0; > u64 ts0, ts1; > @@ -290,7 +290,7 @@ static void __csd_lock_wait(struct __call_single_data *csd) > smp_acquire__after_ctrl_dep(); > } > > -static __always_inline void csd_lock_wait(struct __call_single_data *csd) > +static __always_inline void csd_lock_wait(call_single_data_t *csd) > { > if (static_branch_unlikely(&csdlock_debug_enabled)) { > __csd_lock_wait(csd); > @@ -300,17 +300,17 @@ static __always_inline void csd_lock_wait(struct __call_single_data *csd) > smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK)); > } > #else > -static void csd_lock_record(struct __call_single_data *csd) > +static void csd_lock_record(call_single_data_t *csd) > { > } > > -static __always_inline void csd_lock_wait(struct __call_single_data *csd) > +static __always_inline void csd_lock_wait(call_single_data_t *csd) > { > smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK)); > } > #endif > > -static __always_inline void csd_lock(struct __call_single_data *csd) > +static __always_inline void csd_lock(call_single_data_t *csd) > { > csd_lock_wait(csd); > csd->node.u_flags |= CSD_FLAG_LOCK; > @@ -323,7 +323,7 @@ static __always_inline void csd_lock(struct __call_single_data *csd) > smp_wmb(); > } > > -static __always_inline void csd_unlock(struct __call_single_data *csd) > +static __always_inline void csd_unlock(call_single_data_t *csd) > { > WARN_ON(!(csd->node.u_flags & CSD_FLAG_LOCK)); > > @@ -376,7 +376,7 @@ 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, struct __call_single_data *csd) > +static int generic_exec_single(int cpu, call_single_data_t *csd) > { > if (cpu == smp_processor_id()) { > smp_call_func_t func = csd->func; > @@ -667,7 +667,7 @@ EXPORT_SYMBOL(smp_call_function_single); > * > * Return: %0 on success or negative errno value on error > */ > -int smp_call_function_single_async(int cpu, struct __call_single_data *csd) > +int smp_call_function_single_async(int cpu, call_single_data_t *csd) > { > int err = 0; > > diff --git a/kernel/up.c b/kernel/up.c > index a38b8b095251..df50828cc2f0 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, struct __call_single_data *csd) > +int smp_call_function_single_async(int cpu, call_single_data_t *csd) > { > unsigned long flags; > > -- > 2.42.0 >
-- Best Regards Guo Ren
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