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SubjectRe: [PATCH 06/19] dlm: align midcomms message buffer
On Sat, 26 Jan 2008, Andrew Morton wrote:

>> On Thu, 24 Jan 2008 10:50:29 -0600 David Teigland <teigland@redhat.com> wrote:
>> From: Fabio M. Di Nitto <fabbione@ubuntu.com>
>>
>> gcc does not guarantee that a static buffer is 64bit aligned. This change
>> allows sparc64 to work.
>>
>
> This buffer is not static: changelog needs fixing: s/static/auto/
>
>> ---
>> fs/dlm/midcomms.c | 2 +-
>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
>> index f8c69dd..da653b5 100644
>> --- a/fs/dlm/midcomms.c
>> +++ b/fs/dlm/midcomms.c
>> @@ -58,7 +58,7 @@ static void copy_from_cb(void *dst, const void *base, unsigned offset,
>> int dlm_process_incoming_buffer(int nodeid, const void *base,
>> unsigned offset, unsigned len, unsigned limit)
>> {
>> - unsigned char __tmp[DLM_INBUF_LEN];
>> + unsigned char __tmp[DLM_INBUF_LEN] __attribute__((aligned(64)));
>> struct dlm_header *msg = (struct dlm_header *) __tmp;
>> int ret = 0;
>> int err = 0;
>
> Why does DLM require that this thing be 64-bit aligned?
>
> It all looks rather ugly. Can't this stuff be implemeted within the C type
> system somehow?
>

how about this one:

From adfe3b0654583d34b0840d20a69e4306d5b98caf Mon Sep 17 00:00:00 2001
Message-Id: <adfe3b0654583d34b0840d20a69e4306d5b98caf.1201584946.git.fabbione@ubuntu.com>
From: Fabio M. Di Nitto <fabbione@ubuntu.com>
Date: Tue, 29 Jan 2008 06:35:20 +0100
Subject: [PATCH 1/1] dlm: align midcomms message buffer

gcc does not guarantee that an auto buffer is 64bit aligned.
This change allows sparc64 to work.

Signed-off-by: Fabio M. Di Nitto <fabbione@ubuntu.com>
---
:100644 100644 f8c69dd... 53b7af2... M fs/dlm/midcomms.c
fs/dlm/midcomms.c | 13 ++++++++-----
1 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index f8c69dd..53b7af2 100644
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -58,8 +58,11 @@ static void copy_from_cb(void *dst, const void *base, unsigned offset,
int dlm_process_incoming_buffer(int nodeid, const void *base,
unsigned offset, unsigned len, unsigned limit)
{
- unsigned char __tmp[DLM_INBUF_LEN];
- struct dlm_header *msg = (struct dlm_header *) __tmp;
+ union {
+ unsigned char __buf[DLM_INBUF_LEN];
+ struct dlm_header dlm;
+ } __tmp;
+ struct dlm_header *msg = &__tmp.dlm;
int ret = 0;
int err = 0;
uint16_t msglen;
@@ -100,8 +103,8 @@ int dlm_process_incoming_buffer(int nodeid, const void *base,
in the buffer on the stack (which should work for most
ordinary messages). */

- if (msglen > sizeof(__tmp) &&
- msg == (struct dlm_header *) __tmp) {
+ if (msglen > DLM_INBUF_LEN &&
+ msg == &__tmp.dlm) {
msg = kmalloc(dlm_config.ci_buffer_size, GFP_KERNEL);
if (msg == NULL)
return ret;
@@ -119,7 +122,7 @@ int dlm_process_incoming_buffer(int nodeid, const void *base,
dlm_receive_buffer(msg, nodeid);
}

- if (msg != (struct dlm_header *) __tmp)
+ if (msg != &__tmp.dlm)
kfree(msg);

return err ? err : ret;
--
1.5.3.8

--
I'm going to make him an offer he can't refuse.


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