From: Ingo Molnar <mingo@kernel.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
"David S. Miller" <davem@davemloft.net>,
Ard Biesheuvel <ardb@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: [PATCH] per_task: Remove the PER_TASK_BYTES hard-coded constant
Date: Tue, 4 Jan 2022 15:10:51 +0100 [thread overview]
Message-ID: <YdRVawyDbHvI01uV@gmail.com> (raw)
In-Reply-To: <YdLaMvaM9vq4W6f1@gmail.com>
* Ingo Molnar <mingo@kernel.org> wrote:
> There's one thing ugly about it, the fixed PER_TASK_BYTES limit, I plan
> to make ->per_task_array[] the last field of task_struct, i.e. change it
> to:
>
> u8 per_task_area[];
>
> This actually became possible through the fixing of the x86 FPU code in the
> following fast-headers commit:
>
> 4ae0f28bc1c8 headers/deps: x86/fpu: Make task_struct::thread constant size
So I implemented this approach - the patch below removes the PER_TASK_BYTES
hard-coded limit.
( Didn't make it variable size via per_task_area[] though - we *do* know
its size after all at build time already, and known-size structures are
better in general than tail-variable-array solutions:
- They work better with static checkers,
- and we actually want the offsets into thread_info to be small on embedded platforms
etc. )
Thanks,
Ingo
============================>
From: Ingo Molnar <mingo@kernel.org>
Date: Tue, 4 Jan 2022 13:48:05 +0100
Subject: [PATCH] per_task: Remove the PER_TASK_BYTES hard-coded constant
- Also remove the unnecessary <linux/sched/per_task_types.h> header.
Not-Signed-off-by-yet: Ingo Molnar <mingo@kernel.org>
---
include/linux/sched/per_task.h | 3 ++-
include/linux/sched/per_task_types.h | 7 -------
kernel/sched/core.c | 4 ++++
3 files changed, 6 insertions(+), 8 deletions(-)
diff --git a/include/linux/sched/per_task.h b/include/linux/sched/per_task.h
index e20837e82681..a10538713a26 100644
--- a/include/linux/sched/per_task.h
+++ b/include/linux/sched/per_task.h
@@ -37,7 +37,6 @@
* A build-time check ensures that we haven't run out of available space.
*/
-#include <linux/sched/per_task_types.h>
#include <linux/compiler.h>
#ifndef __PER_TASK_GEN
@@ -61,4 +60,6 @@
#define per_task_container_of(var, name) container_of((void *)(var) - per_task_offset(name), struct task_struct, per_task_area[0])
+#define PER_TASK_BYTES (per_task_offset(_end))
+
#endif /* _LINUX_SCHED_PER_TASK_H */
diff --git a/include/linux/sched/per_task_types.h b/include/linux/sched/per_task_types.h
deleted file mode 100644
index 8af8c10f8dae..000000000000
--- a/include/linux/sched/per_task_types.h
+++ /dev/null
@@ -1,7 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _LINUX_SCHED_PER_TASK_TYPES_H
-#define _LINUX_SCHED_PER_TASK_TYPES_H
-
-#define PER_TASK_BYTES 8192
-
-#endif /* _LINUX_SCHED_PER_TASK_TYPES_H */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index bc38b19f6398..fdb5b99ae6e0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -89,6 +89,8 @@
#include "../../fs/io-wq.h"
#include "../smpboot.h"
+#include "../../../kernel/sched/per_task_area_struct.h"
+
DEFINE_PER_TASK(unsigned int, flags);
#ifdef CONFIG_THREAD_INFO_IN_TASK
@@ -9481,6 +9483,8 @@ void __init per_task_init(void)
{
unsigned long per_task_bytes = per_task_offset(_end);
+ printk("per_task: sizeof(struct task_struct): %ld bytes\n", sizeof(struct task_struct));
+ printk("per_task: sizeof(struct task_struct_per_task): %ld bytes\n", sizeof(struct task_struct_per_task));
printk("per_task: Using %ld per_task bytes, %ld bytes available\n", per_task_bytes, (long)PER_TASK_BYTES);
BUG_ON(per_task_offset(_end) > PER_TASK_BYTES);
next prev parent reply other threads:[~2022-01-04 14:10 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-02 21:57 [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Ingo Molnar
2022-01-03 10:11 ` Greg Kroah-Hartman
2022-01-03 11:12 ` Ingo Molnar
2022-01-03 13:46 ` Greg Kroah-Hartman
2022-01-03 16:29 ` Ingo Molnar
2022-01-10 10:28 ` Peter Zijlstra
2022-01-04 14:10 ` Ingo Molnar [this message]
2022-01-04 15:14 ` [PATCH] per_task: Remove the PER_TASK_BYTES hard-coded constant Andy Shevchenko
2022-01-04 23:27 ` Ingo Molnar
2022-01-04 17:51 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Arnd Bergmann
2022-01-05 0:05 ` Ingo Molnar
2022-01-05 1:37 ` Arnd Bergmann
2022-01-05 9:37 ` Andy Shevchenko
2022-01-04 14:05 ` [PATCH] per_task: Implement single template to define 'struct task_struct_per_task' fields and offsets Ingo Molnar
2022-01-03 13:54 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Kirill A. Shutemov
2022-01-04 10:54 ` Ingo Molnar
2022-01-04 13:34 ` Greg Kroah-Hartman
2022-01-04 13:54 ` [PATCH] headers/uninline: Uninline single-use function: kobject_has_children() Ingo Molnar
2022-01-04 15:09 ` Greg Kroah-Hartman
2022-01-04 15:14 ` Greg Kroah-Hartman
2022-01-05 0:11 ` Ingo Molnar
2022-01-05 15:23 ` Greg Kroah-Hartman
2022-01-06 11:26 ` Ingo Molnar
2022-01-03 17:54 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Nathan Chancellor
2022-01-04 10:47 ` Ingo Molnar
2022-01-04 10:56 ` [DEBUG PATCH] DO NOT MERGE: Enable SHADOW_CALL_STACK on GCC builds, for build testing Ingo Molnar
2022-01-04 11:02 ` [PATCH] headers/deps: dcache: Move the ____cacheline_aligned attribute to the head of the definition Ingo Molnar
2022-01-04 15:05 ` kernel test robot
2022-01-04 17:51 ` Nathan Chancellor
2022-01-05 0:20 ` Ingo Molnar
2022-01-05 0:26 ` [PATCH] headers/deps: Attribute placement fixes for Clang & GCC Ingo Molnar
2022-01-04 11:19 ` [TREE] "Fast Kernel Headers" Tree WIP/development branch Ingo Molnar
2022-01-04 17:25 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Nick Desaulniers
2022-01-05 0:43 ` Ingo Molnar
2022-01-04 17:50 ` Nathan Chancellor
2022-01-05 0:35 ` [PATCH] x86/kbuild: Enable CONFIG_KALLSYMS_ALL=y in the defconfigs Ingo Molnar
2022-01-08 21:57 ` [tip: x86/build] " tip-bot2 for Ingo Molnar
2022-01-05 0:40 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Ingo Molnar
2022-01-05 1:07 ` Ingo Molnar
2022-01-05 5:20 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel'\''s "Dependency Hell Paul Zimmerman
2022-01-05 21:42 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Nathan Chancellor
2022-01-08 10:32 ` [PATCH] headers/deps: Add header dependencies to .c files: <linux/ptrace_api.h> Ingo Molnar
2022-01-08 11:08 ` [PATCH] FIX: headers/deps: uapi/headers: Create usr/include/uapi symbolic link Ingo Molnar
2022-01-08 11:18 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Ingo Molnar
2022-01-08 11:38 ` [PATCH] x86/bitops: Remove unused __sw_hweight64() assembly implementation Ingo Molnar
2022-01-08 11:49 ` [PATCH 0000/2297] [ANNOUNCE, RFC] "Fast Kernel Headers" Tree -v1: Eliminate the Linux kernel's "Dependency Hell" Ingo Molnar
2022-01-08 12:17 ` Ingo Molnar
2022-01-10 20:03 ` Nathan Chancellor
2022-01-10 20:05 ` Nathan Chancellor
2022-01-05 22:33 ` Nathan Chancellor
2022-01-08 15:16 ` Ingo Molnar
2022-01-07 0:29 ` Nathan Chancellor
2022-01-08 11:54 ` Ingo Molnar
2022-01-04 12:36 ` Willy Tarreau
2022-01-04 16:05 ` Andy Shevchenko
2022-01-04 16:18 ` Andy Shevchenko
2022-01-15 0:42 ` Paul E. McKenney
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