Re: [PATCH 1/8] percpu: add __percpu sparse annotations to corekernel subsystems

From: Paul E. McKenney
Date: Sun Jan 31 2010 - 06:43:00 EST

On Tue, Jan 26, 2010 at 12:22:08AM +0900, Tejun Heo wrote:
> Add __percpu sparse annotations to core subsystems.
>
> These annotations are to make sparse consider percpu variables to be
> in a different address space and warn if accessed without going
> through percpu accessors. This patch doesn't affect normal builds.

The RCU pieces look fine to me.

Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>

> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Jens Axboe <axboe@xxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Dipankar Sarma <dipankar@xxxxxxxxxx>
> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
> ---
> include/linux/blktrace_api.h | 4 ++--
> include/linux/genhd.h | 2 +-
> include/linux/kexec.h | 2 +-
> include/linux/mmzone.h | 2 +-
> include/linux/module.h | 2 +-
> include/linux/percpu_counter.h | 2 +-
> include/linux/srcu.h | 2 +-
> kernel/kexec.c | 2 +-
> kernel/sched.c | 4 ++--
> kernel/stop_machine.c | 2 +-
> mm/percpu.c | 18 ++++++++++--------
> 11 files changed, 22 insertions(+), 20 deletions(-)
>
> diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
> index 3b73b99..416bf62 100644
> --- a/include/linux/blktrace_api.h
> +++ b/include/linux/blktrace_api.h
> @@ -150,8 +150,8 @@ struct blk_user_trace_setup {
> struct blk_trace {
> int trace_state;
> struct rchan *rchan;
> - unsigned long *sequence;
> - unsigned char *msg_data;
> + unsigned long __percpu *sequence;
> + unsigned char __percpu *msg_data;
> u16 act_mask;
> u64 start_lba;
> u64 end_lba;
> diff --git a/include/linux/genhd.h b/include/linux/genhd.h
> index 9717081..56b5051 100644
> --- a/include/linux/genhd.h
> +++ b/include/linux/genhd.h
> @@ -101,7 +101,7 @@ struct hd_struct {
> unsigned long stamp;
> int in_flight[2];
> #ifdef CONFIG_SMP
> - struct disk_stats *dkstats;
> + struct disk_stats __percpu *dkstats;
> #else
> struct disk_stats dkstats;
> #endif
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index c356b69..03e8e8d 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -199,7 +199,7 @@ extern struct kimage *kexec_crash_image;
> */
> extern struct resource crashk_res;
> typedef u32 note_buf_t[KEXEC_NOTE_BYTES/4];
> -extern note_buf_t *crash_notes;
> +extern note_buf_t __percpu *crash_notes;
> extern u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
> extern size_t vmcoreinfo_size;
> extern size_t vmcoreinfo_max_size;
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 7874201..41acd4b 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -301,7 +301,7 @@ struct zone {
> unsigned long min_unmapped_pages;
> unsigned long min_slab_pages;
> #endif
> - struct per_cpu_pageset *pageset;
> + struct per_cpu_pageset __percpu *pageset;
> /*
> * free areas of different sizes
> */
> diff --git a/include/linux/module.h b/include/linux/module.h
> index 7e74ae0..dd618eb 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -365,7 +365,7 @@ struct module
>
> struct module_ref {
> int count;
> - } *refptr;
> + } __percpu *refptr;
> #endif
>
> #ifdef CONFIG_CONSTRUCTORS
> diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
> index a7684a5..9bd103c 100644
> --- a/include/linux/percpu_counter.h
> +++ b/include/linux/percpu_counter.h
> @@ -21,7 +21,7 @@ struct percpu_counter {
> #ifdef CONFIG_HOTPLUG_CPU
> struct list_head list; /* All percpu_counters are on a list */
> #endif
> - s32 *counters;
> + s32 __percpu *counters;
> };
>
> extern int percpu_counter_batch;
> diff --git a/include/linux/srcu.h b/include/linux/srcu.h
> index 4765d97..41eedcc 100644
> --- a/include/linux/srcu.h
> +++ b/include/linux/srcu.h
> @@ -33,7 +33,7 @@ struct srcu_struct_array {
>
> struct srcu_struct {
> int completed;
> - struct srcu_struct_array *per_cpu_ref;
> + struct srcu_struct_array __percpu *per_cpu_ref;
> struct mutex mutex;
> };
>
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index a9a93d9..c769613 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -40,7 +40,7 @@
> #include <asm/sections.h>
>
> /* Per cpu memory for storing cpu states in case of system crash. */
> -note_buf_t* crash_notes;
> +note_buf_t __percpu *crash_notes;
>
> /* vmcoreinfo stuff */
> static unsigned char vmcoreinfo_data[VMCOREINFO_BYTES];
> diff --git a/kernel/sched.c b/kernel/sched.c
> index 4508fe7..512b10f 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -1566,7 +1566,7 @@ static unsigned long cpu_avg_load_per_task(int cpu)
>
> #ifdef CONFIG_FAIR_GROUP_SCHED
>
> -static __read_mostly unsigned long *update_shares_data;
> +static __read_mostly unsigned long __percpu *update_shares_data;
>
> static void __set_se_shares(struct sched_entity *se, unsigned long shares);
>
> @@ -10668,7 +10668,7 @@ struct cgroup_subsys cpu_cgroup_subsys = {
> struct cpuacct {
> struct cgroup_subsys_state css;
> /* cpuusage holds pointer to a u64-type object on every cpu */
> - u64 *cpuusage;
> + u64 __percpu *cpuusage;
> struct percpu_counter cpustat[CPUACCT_STAT_NSTATS];
> struct cpuacct *parent;
> };
> diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
> index 912823e..9bb9fb1 100644
> --- a/kernel/stop_machine.c
> +++ b/kernel/stop_machine.c
> @@ -45,7 +45,7 @@ static int refcount;
> static struct workqueue_struct *stop_machine_wq;
> static struct stop_machine_data active, idle;
> static const struct cpumask *active_cpus;
> -static void *stop_machine_work;
> +static void __percpu *stop_machine_work;
>
> static void set_state(enum stopmachine_state newstate)
> {
> diff --git a/mm/percpu.c b/mm/percpu.c
> index b336638..768419d 100644
> --- a/mm/percpu.c
> +++ b/mm/percpu.c
> @@ -80,13 +80,15 @@
> /* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
> #ifndef __addr_to_pcpu_ptr
> #define __addr_to_pcpu_ptr(addr) \
> - (void *)((unsigned long)(addr) - (unsigned long)pcpu_base_addr \
> - + (unsigned long)__per_cpu_start)
> + (void __percpu *)((unsigned long)(addr) - \
> + (unsigned long)pcpu_base_addr + \
> + (unsigned long)__per_cpu_start)
> #endif
> #ifndef __pcpu_ptr_to_addr
> #define __pcpu_ptr_to_addr(ptr) \
> - (void *)((unsigned long)(ptr) + (unsigned long)pcpu_base_addr \
> - - (unsigned long)__per_cpu_start)
> + (void __force *)((unsigned long)(ptr) + \
> + (unsigned long)pcpu_base_addr - \
> + (unsigned long)__per_cpu_start)
> #endif
>
> struct pcpu_chunk {
> @@ -1065,7 +1067,7 @@ static struct pcpu_chunk *alloc_pcpu_chunk(void)
> * RETURNS:
> * Percpu pointer to the allocated area on success, NULL on failure.
> */
> -static void *pcpu_alloc(size_t size, size_t align, bool reserved)
> +static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved)
> {
> static int warn_limit = 10;
> struct pcpu_chunk *chunk;
> @@ -1194,7 +1196,7 @@ fail_unlock_mutex:
> * RETURNS:
> * Percpu pointer to the allocated area on success, NULL on failure.
> */
> -void *__alloc_percpu(size_t size, size_t align)
> +void __percpu *__alloc_percpu(size_t size, size_t align)
> {
> return pcpu_alloc(size, align, false);
> }
> @@ -1215,7 +1217,7 @@ EXPORT_SYMBOL_GPL(__alloc_percpu);
> * RETURNS:
> * Percpu pointer to the allocated area on success, NULL on failure.
> */
> -void *__alloc_reserved_percpu(size_t size, size_t align)
> +void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
> {
> return pcpu_alloc(size, align, true);
> }
> @@ -1267,7 +1269,7 @@ static void pcpu_reclaim(struct work_struct *work)
> * CONTEXT:
> * Can be called from atomic context.
> */
> -void free_percpu(void *ptr)
> +void free_percpu(void __percpu *ptr)
> {
> void *addr;
> struct pcpu_chunk *chunk;
> --
> 1.6.4.2
>
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