From bcf9033e5449bdcaa9bed46467a7141a8049dadb Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 14 Sep 2021 14:10:33 +0200 Subject: [PATCH] sched: move CPU field back into thread_info if THREAD_INFO_IN_TASK=y THREAD_INFO_IN_TASK moved the CPU field out of thread_info, but this causes some issues on architectures that define raw_smp_processor_id() in terms of this field, due to the fact that #include'ing linux/sched.h to get at struct task_struct is problematic in terms of circular dependencies. Given that thread_info and task_struct are the same data structure anyway when THREAD_INFO_IN_TASK=y, let's move it back so that having access to the type definition of struct thread_info is sufficient to reference the CPU number of the current task. Note that this requires THREAD_INFO_IN_TASK's definition of the task_thread_info() helper to be updated, as task_cpu() takes a pointer-to-const, whereas task_thread_info() (which is used to generate lvalues as well), needs a non-const pointer. So make it a macro instead. Signed-off-by: Ard Biesheuvel Acked-by: Catalin Marinas Acked-by: Mark Rutland Acked-by: Michael Ellerman --- arch/arm64/kernel/asm-offsets.c | 1 - arch/arm64/kernel/head.S | 2 +- arch/powerpc/kernel/asm-offsets.c | 2 +- arch/powerpc/kernel/smp.c | 2 +- include/linux/sched.h | 13 +------------ kernel/sched/sched.h | 4 ---- 6 files changed, 4 insertions(+), 20 deletions(-) diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index cee9f3e9f906..0bfc048221af 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -27,7 +27,6 @@ int main(void) { DEFINE(TSK_ACTIVE_MM, offsetof(struct task_struct, active_mm)); - DEFINE(TSK_CPU, offsetof(struct task_struct, cpu)); BLANK(); DEFINE(TSK_TI_CPU, offsetof(struct task_struct, thread_info.cpu)); DEFINE(TSK_TI_FLAGS, offsetof(struct task_struct, thread_info.flags)); diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 17962452e31d..6a98f1a38c29 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -412,7 +412,7 @@ SYM_FUNC_END(__create_page_tables) scs_load \tsk adr_l \tmp1, __per_cpu_offset - ldr w\tmp2, [\tsk, #TSK_CPU] + ldr w\tmp2, [\tsk, #TSK_TI_CPU] ldr \tmp1, [\tmp1, \tmp2, lsl #3] set_this_cpu_offset \tmp1 .endm diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index e563d3222d69..e37e4546034e 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -93,7 +93,7 @@ int main(void) #endif /* CONFIG_PPC64 */ OFFSET(TASK_STACK, task_struct, stack); #ifdef CONFIG_SMP - OFFSET(TASK_CPU, task_struct, cpu); + OFFSET(TASK_CPU, task_struct, thread_info.cpu); #endif #ifdef CONFIG_LIVEPATCH diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 9cc7d3dbf439..512d875b45e0 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -1223,7 +1223,7 @@ static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle) paca_ptrs[cpu]->kstack = (unsigned long)task_stack_page(idle) + THREAD_SIZE - STACK_FRAME_OVERHEAD; #endif - idle->cpu = cpu; + task_thread_info(idle)->cpu = cpu; secondary_current = current_set[cpu] = idle; } diff --git a/include/linux/sched.h b/include/linux/sched.h index 39039ce8ac4c..8699594e3f99 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -750,10 +750,6 @@ struct task_struct { #ifdef CONFIG_SMP int on_cpu; struct __call_single_node wake_entry; -#ifdef CONFIG_THREAD_INFO_IN_TASK - /* Current CPU: */ - unsigned int cpu; -#endif unsigned int wakee_flips; unsigned long wakee_flip_decay_ts; struct task_struct *last_wakee; @@ -1886,10 +1882,7 @@ extern struct thread_info init_thread_info; extern unsigned long init_stack[THREAD_SIZE / sizeof(unsigned long)]; #ifdef CONFIG_THREAD_INFO_IN_TASK -static inline struct thread_info *task_thread_info(struct task_struct *task) -{ - return &task->thread_info; -} +# define task_thread_info(task) (&(task)->thread_info) #elif !defined(__HAVE_THREAD_FUNCTIONS) # define task_thread_info(task) ((struct thread_info *)(task)->stack) #endif @@ -2114,11 +2107,7 @@ static __always_inline bool need_resched(void) static inline unsigned int task_cpu(const struct task_struct *p) { -#ifdef CONFIG_THREAD_INFO_IN_TASK - return READ_ONCE(p->cpu); -#else return READ_ONCE(task_thread_info(p)->cpu); -#endif } extern void set_task_cpu(struct task_struct *p, unsigned int cpu); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 3d3e5793e117..79fcbad11450 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1926,11 +1926,7 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu) * per-task data have been completed by this moment. */ smp_wmb(); -#ifdef CONFIG_THREAD_INFO_IN_TASK - WRITE_ONCE(p->cpu, cpu); -#else WRITE_ONCE(task_thread_info(p)->cpu, cpu); -#endif p->wake_cpu = cpu; #endif }