[v5] Compiler-Based Context- and Locking-Analysis

[PATCH v5 12/36] bit_spinlock: Include missing <asm/processor.h>

Posted by Marco Elver 1 month, 3 weeks ago

Including <linux/bit_spinlock.h> into an empty TU will result in the
compiler complaining:

./include/linux/bit_spinlock.h:34:4: error: call to undeclared function 'cpu_relax'; <...>
   34 |                         cpu_relax();
      |                         ^
1 error generated.

Include <asm/processor.h> to allow including bit_spinlock.h where
<asm/processor.h> is not otherwise included.

Signed-off-by: Marco Elver <elver@google.com>
---
 include/linux/bit_spinlock.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/bit_spinlock.h b/include/linux/bit_spinlock.h
index c0989b5b0407..59e345f74b0e 100644
--- a/include/linux/bit_spinlock.h
+++ b/include/linux/bit_spinlock.h
@@ -7,6 +7,8 @@
 #include <linux/atomic.h>
 #include <linux/bug.h>
 
+#include <asm/processor.h>  /* for cpu_relax() */
+
 /*
  *  bit-based spin_lock()
  *
-- 
2.52.0.322.g1dd061c0dc-goog

Re: [PATCH v5 12/36] bit_spinlock: Include missing <asm/processor.h>

Posted by Bart Van Assche 1 month, 2 weeks ago

On 12/19/25 7:40 AM, Marco Elver wrote:
> Including <linux/bit_spinlock.h> into an empty TU will result in the
> compiler complaining:
> 
> ./include/linux/bit_spinlock.h:34:4: error: call to undeclared function 'cpu_relax'; <...>
>     34 |                         cpu_relax();
>        |                         ^
> 1 error generated.
> 
> Include <asm/processor.h> to allow including bit_spinlock.h where
> <asm/processor.h> is not otherwise included.
> 
> Signed-off-by: Marco Elver <elver@google.com>
> ---
>   include/linux/bit_spinlock.h | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/include/linux/bit_spinlock.h b/include/linux/bit_spinlock.h
> index c0989b5b0407..59e345f74b0e 100644
> --- a/include/linux/bit_spinlock.h
> +++ b/include/linux/bit_spinlock.h
> @@ -7,6 +7,8 @@
>   #include <linux/atomic.h>
>   #include <linux/bug.h>
>   
> +#include <asm/processor.h>  /* for cpu_relax() */
> +
>   /*
>    *  bit-based spin_lock()
>    *

The abbreviation "TU" is uncommon so it's probably a good idea to expand
it. Anyway:

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

[tip: locking/core] bit_spinlock: Include missing <asm/processor.h>

Posted by tip-bot2 for Marco Elver 1 month ago

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     5f7ba059710609bb997d50775ba92fbf29be51da
Gitweb:        https://git.kernel.org/tip/5f7ba059710609bb997d50775ba92fbf29be51da
Author:        Marco Elver <elver@google.com>
AuthorDate:    Fri, 19 Dec 2025 16:40:01 +01:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 05 Jan 2026 16:43:29 +01:00

bit_spinlock: Include missing <asm/processor.h>

Including <linux/bit_spinlock.h> into an empty TU will result in the
compiler complaining:

./include/linux/bit_spinlock.h:34:4: error: call to undeclared function 'cpu_relax'; <...>
   34 |                         cpu_relax();
      |                         ^
1 error generated.

Include <asm/processor.h> to allow including bit_spinlock.h where
<asm/processor.h> is not otherwise included.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://patch.msgid.link/20251219154418.3592607-13-elver@google.com
---
 include/linux/bit_spinlock.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/bit_spinlock.h b/include/linux/bit_spinlock.h
index c0989b5..59e345f 100644
--- a/include/linux/bit_spinlock.h
+++ b/include/linux/bit_spinlock.h
@@ -7,6 +7,8 @@
 #include <linux/atomic.h>
 #include <linux/bug.h>
 
+#include <asm/processor.h>  /* for cpu_relax() */
+
 /*
  *  bit-based spin_lock()
  *