Messages in this thread Patches in this message | | | Date | Thu, 16 Jun 2011 14:03:36 +0100 | Subject | [PATCH] ring_buffer: Ensure that buffer page data is aligned. | From | Will Newton <> |
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Explicitly align the start of the buffer page data array to the required arch alignment. This is required for architectures that require 8 byte alignment but do not have a 8 byte local_t.
Signed-off-by: Will Newton <will.newton@imgtec.com> --- kernel/trace/ring_buffer.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-)
I don't believe that any currently in-tree architecture is affected by this, but it can be an issue on 32bit architectures that require an 8 byte aligment but only have a 32bit local_t. I think it's potentially cleaner to make the alignment explicit anyway.
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 0ef7b4b..36d5699 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -215,6 +215,8 @@ EXPORT_SYMBOL_GPL(tracing_is_on); # define RB_ARCH_ALIGNMENT 8U #endif
+#define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT) + /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX
@@ -363,7 +365,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data); struct buffer_data_page { u64 time_stamp; /* page time stamp */ local_t commit; /* write committed index */ - unsigned char data[]; /* data of buffer page */ + unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ };
/* -- 1.7.3.4From 356f15b861c41a65d4550358ab368fa01c36c77c Mon Sep 17 00:00:00 2001 From: Will Newton <will.newton@imgtec.com> Date: Thu, 16 Jun 2011 13:38:59 +0100 Subject: [PATCH] ring_buffer: Ensure that buffer page data is aligned.
Explicitly align the start of the buffer page data array to the required arch alignment. This is required for architectures that require 8 byte alignment but do not have a 8 byte local_t.
Signed-off-by: Will Newton <will.newton@imgtec.com> --- kernel/trace/ring_buffer.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 0ef7b4b..36d5699 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -215,6 +215,8 @@ EXPORT_SYMBOL_GPL(tracing_is_on); # define RB_ARCH_ALIGNMENT 8U #endif +#define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT) + /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX @@ -363,7 +365,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data); struct buffer_data_page { u64 time_stamp; /* page time stamp */ local_t commit; /* write committed index */ - unsigned char data[]; /* data of buffer page */ + unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ }; /* -- 1.7.3.4
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