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Message-Id: <20210914121036.3975026-6-ardb@kernel.org>
Date: Tue, 14 Sep 2021 14:10:33 +0200
From: Ard Biesheuvel <ardb@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Ard Biesheuvel <ardb@...nel.org>,
Keith Packard <keithpac@...zon.com>,
Russell King <linux@...linux.org.uk>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Michael Ellerman <mpe@...erman.id.au>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Paul Mackerras <paulus@...ba.org>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Heiko Carstens <hca@...ux.ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>,
Christian Borntraeger <borntraeger@...ibm.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Peter Zijlstra <peterz@...radead.org>,
Kees Cook <keescook@...omium.org>,
Andy Lutomirski <luto@...nel.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Arnd Bergmann <arnd@...db.de>,
linux-arm-kernel@...ts.infradead.org,
linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org,
linux-s390@...r.kernel.org
Subject: [RFC PATCH 5/8] 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.
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
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 | 6 +-----
kernel/sched/sched.h | 4 ----
6 files changed, 4 insertions(+), 13 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 e12b524426b0..37aa521078e7 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;
@@ -2114,7 +2110,7 @@ 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);
+ return READ_ONCE(p->thread_info.cpu);
#else
return READ_ONCE(task_thread_info(p)->cpu);
#endif
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
}
--
2.30.2
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