Introduce flags for reserve_bootmem()

This patchset adds a flags variable to reserve_bootmem() and uses the
BOOTMEM_EXCLUSIVE flag in crashkernel reservation code to detect collisions
between crashkernel area and already used memory.

This patch:

Change the reserve_bootmem() function to accept a new flag BOOTMEM_EXCLUSIVE.
If that flag is set, the function returns with -EBUSY if the memory already
has been reserved in the past.  This is to avoid conflicts.

Because that code runs before SMP initialisation, there's no race condition
inside reserve_bootmem_core().

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix powerpc build]
Signed-off-by: Bernhard Walle <bwalle@suse.de>
Cc: <linux-arch@vger.kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 2 deletions

diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h
index 0365ec9fc0c9..4e4e340592fb 100644
--- a/include/linux/bootmem.h
+++ b/include/linux/bootmem.h
@@ -60,8 +60,20 @@ extern void *__alloc_bootmem_core(struct bootmem_data *bdata,
                                   unsigned long goal,
                                   unsigned long limit);
 
+/*
+ * flags for reserve_bootmem (also if CONFIG_HAVE_ARCH_BOOTMEM_NODE,
+ * the architecture-specific code should honor this)
+ */
+#define BOOTMEM_DEFAULT         0
+#define BOOTMEM_EXCLUSIVE       (1<<0)
+
 #ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
-extern void reserve_bootmem(unsigned long addr, unsigned long size);
+/*
+ * If flags is 0, then the return value is always 0 (success). If
+ * flags contains BOOTMEM_EXCLUSIVE, then -EBUSY is returned if the
+ * memory already was reserved.
+ */
+extern int reserve_bootmem(unsigned long addr, unsigned long size, int flags);
 #define alloc_bootmem(x) \
         __alloc_bootmem(x, SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS))
 #define alloc_bootmem_low(x) \
@@ -84,7 +96,8 @@ extern unsigned long init_bootmem_node(pg_data_t *pgdat,
                                        unsigned long endpfn);
 extern void reserve_bootmem_node(pg_data_t *pgdat,
                                  unsigned long physaddr,
-                                 unsigned long size);
+                                 unsigned long size,
+                                 int flags);
 extern void free_bootmem_node(pg_data_t *pgdat,
                               unsigned long addr,
                               unsigned long size);