lkml.org 
[lkml]   [2011]   [Nov]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] percpu: add comment to per_cpu_ptr_to_phys
add comments about current per_cpu_ptr_to_phys implementation
to explain why the logic is more complicated than necessary.

Signed-off-by: Dave Young <dyoung@redhat.com>
---
mm/percpu.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

--- linux-2.6.orig/mm/percpu.c 2011-11-22 10:18:46.000000000 +0800
+++ linux-2.6/mm/percpu.c 2011-11-23 16:27:01.667562973 +0800
@@ -988,6 +988,19 @@ phys_addr_t per_cpu_ptr_to_phys(void *ad
unsigned int cpu;

/*
+ * percpu allocator has special setup for the first chunk,
+ * which currently supports either embedding in linear address space
+ * or vmalloc mapping, and, from the second one, the backing
+ * allocator (currently either vm or km) provides translation.
+ *
+ * The addr can be tranlated simply without checking if it falls
+ * into the first chunk. But the current code reflects better
+ * how percpu allocator actually works, and the verification can
+ * discover both bugs in percpu allocator itself and
+ * per_cpu_ptr_to_phys() callers. So we keep current code.
+ */
+
+ /*
* The following test on first_start/end isn't strictly
* necessary but will speed up lookups of addresses which
* aren't in the first chunk.

\
 
 \ /
  Last update: 2011-11-23 09:45    [W:0.139 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site