locking: Detect includes rwlock.h outside of spinlock.h

From: Michael S. Tsirkin <mst@redhat.com>

The check for __LINUX_SPINLOCK_H within rwlock.h (and other files)
detects the direct include of the header file if it is at the very
beginning of the include section.
If it is listed later then chances are high that spinlock.h was already
included (including rwlock.h) and the additional listing of rwlock.h
will not cause any failure.

On PREEMPT_RT this additional rwlock.h will lead to compile failures
since it uses a different rwlock implementation.

Add __LINUX_INSIDE_SPINLOCK_H to spinlock.h and check for this instead
of __LINUX_SPINLOCK_H to detect wrong includes. This will help detect
direct includes of rwlock.h with without PREEMPT_RT enabled.

[ bigeasy: add remaining __LINUX_SPINLOCK_H user and rewrite
  commit description. ]

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/YweemHxJx7O8rjBx@linutronix.de

diff --git a/include/linux/rwlock.h b/include/linux/rwlock.h
index 8f416c5e929ea865417b426079cc7c76eb47ec42..c0ef596f340b58e0caf76d154bdd16dcc0711eeb 100644 (file)
--- a/include/linux/rwlock.h
+++ b/include/linux/rwlock.h
@@ -1,7 +1,7 @@
 #ifndef __LINUX_RWLOCK_H
 #define __LINUX_RWLOCK_H
 
-#ifndef __LINUX_SPINLOCK_H
+#ifndef __LINUX_INSIDE_SPINLOCK_H
 # error "please don't include this file directly"
 #endif
 

diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index 5c0c5174155d05a5ee3228b7fedd25b8c7a96f9d..1341f7d62da44663d48630991e7455e364430b63 100644 (file)
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __LINUX_SPINLOCK_H
 #define __LINUX_SPINLOCK_H
+#define __LINUX_INSIDE_SPINLOCK_H
 
 /*
  * include/linux/spinlock.h - generic spinlock/rwlock declarations
@@ -492,4 +493,5 @@ int __alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *lock_mask,
 
 void free_bucket_spinlocks(spinlock_t *locks);
 
+#undef __LINUX_INSIDE_SPINLOCK_H
 #endif /* __LINUX_SPINLOCK_H */

diff --git a/include/linux/spinlock_api_smp.h b/include/linux/spinlock_api_smp.h
index 51fa0dab68c4dc6af3c8922694f257ea9db3e2d2..89eb6f4c659c706c1b7376534a25d53a316316b7 100644 (file)
--- a/include/linux/spinlock_api_smp.h
+++ b/include/linux/spinlock_api_smp.h
@@ -1,7 +1,7 @@
 #ifndef __LINUX_SPINLOCK_API_SMP_H
 #define __LINUX_SPINLOCK_API_SMP_H
 
-#ifndef __LINUX_SPINLOCK_H
+#ifndef __LINUX_INSIDE_SPINLOCK_H
 # error "please don't include this file directly"
 #endif
 

diff --git a/include/linux/spinlock_api_up.h b/include/linux/spinlock_api_up.h
index b8ba00ccccdebd44e7ad723c66e772e434e73aa8..819aeba1c87e685bfafaf78e2d781d6e432b9877 100644 (file)
--- a/include/linux/spinlock_api_up.h
+++ b/include/linux/spinlock_api_up.h
@@ -1,7 +1,7 @@
 #ifndef __LINUX_SPINLOCK_API_UP_H
 #define __LINUX_SPINLOCK_API_UP_H
 
-#ifndef __LINUX_SPINLOCK_H
+#ifndef __LINUX_INSIDE_SPINLOCK_H
 # error "please don't include this file directly"
 #endif
 

diff --git a/include/linux/spinlock_rt.h b/include/linux/spinlock_rt.h
index 835aedaf68acd5ab8a6109659ffd8227c755ebec..61c49b16f69ab03ba053ace72c421385309ad713 100644 (file)
--- a/include/linux/spinlock_rt.h
+++ b/include/linux/spinlock_rt.h
@@ -2,7 +2,7 @@
 #ifndef __LINUX_SPINLOCK_RT_H
 #define __LINUX_SPINLOCK_RT_H
 
-#ifndef __LINUX_SPINLOCK_H
+#ifndef __LINUX_INSIDE_SPINLOCK_H
 #error Do not include directly. Use spinlock.h
 #endif
 

diff --git a/include/linux/spinlock_up.h b/include/linux/spinlock_up.h
index 16521074b6f7c8576339fd516401915685800494..c87204247592fd2a037c071eaf1fbf93abd16aeb 100644 (file)
--- a/include/linux/spinlock_up.h
+++ b/include/linux/spinlock_up.h
@@ -1,7 +1,7 @@
 #ifndef __LINUX_SPINLOCK_UP_H
 #define __LINUX_SPINLOCK_UP_H
 
-#ifndef __LINUX_SPINLOCK_H
+#ifndef __LINUX_INSIDE_SPINLOCK_H
 # error "please don't include this file directly"
 #endif