The patch titled
Subject: stackdepot: rename pool_index to pool_index_plus_1
has been added to the -mm mm-unstable branch. Its filename is
stackdepot-rename-pool_index-to-pool_index_plus_1.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/stackdepot-rename-pool_index-to-pool_index_plus_1.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Peter Collingbourne <pcc@xxxxxxxxxx>
Subject: stackdepot: rename pool_index to pool_index_plus_1
Date: Mon, 1 Apr 2024 17:14:58 -0700
Commit 3ee34eabac2a ("lib/stackdepot: fix first entry having a 0-handle")
changed the meaning of the pool_index field to mean "the pool index plus
1". This made the code accessing this field less self-documenting, as
well as causing debuggers such as drgn to not be able to easily remain
compatible with both old and new kernels, because they typically do that
by testing for presence of the new field. Because stackdepot is a
debugging tool, we should make sure that it is debugger friendly.
Therefore, give the field a different name to improve readability as well
as enabling debugger backwards compatibility.
Link: https://lkml.kernel.org/r/20240402001500.53533-1-pcc@xxxxxxxxxx
Link: https://linux-review.googlesource.com/id/Ib3e70c36c1d230dd0a118dc22649b33e768b9f88
Signed-off-by: Peter Collingbourne <pcc@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx>
Acked-by: Marco Elver <elver@xxxxxxxxxx>
Acked-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Omar Sandoval <osandov@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/stackdepot.h | 7 +++----
lib/stackdepot.c | 4 ++--
2 files changed, 5 insertions(+), 6 deletions(-)
--- a/include/linux/stackdepot.h~stackdepot-rename-pool_index-to-pool_index_plus_1
+++ a/include/linux/stackdepot.h
@@ -44,10 +44,9 @@ typedef u32 depot_stack_handle_t;
union handle_parts {
depot_stack_handle_t handle;
struct {
- /* pool_index is offset by 1 */
- u32 pool_index : DEPOT_POOL_INDEX_BITS;
- u32 offset : DEPOT_OFFSET_BITS;
- u32 extra : STACK_DEPOT_EXTRA_BITS;
+ u32 pool_index_plus_1 : DEPOT_POOL_INDEX_BITS;
+ u32 offset : DEPOT_OFFSET_BITS;
+ u32 extra : STACK_DEPOT_EXTRA_BITS;
};
};
--- a/lib/stackdepot.c~stackdepot-rename-pool_index-to-pool_index_plus_1
+++ a/lib/stackdepot.c
@@ -330,7 +330,7 @@ static struct stack_record *depot_pop_fr
stack = current_pool + pool_offset;
/* Pre-initialize handle once. */
- stack->handle.pool_index = pool_index + 1;
+ stack->handle.pool_index_plus_1 = pool_index + 1;
stack->handle.offset = pool_offset >> DEPOT_STACK_ALIGN;
stack->handle.extra = 0;
INIT_LIST_HEAD(&stack->hash_list);
@@ -441,7 +441,7 @@ static struct stack_record *depot_fetch_
const int pools_num_cached = READ_ONCE(pools_num);
union handle_parts parts = { .handle = handle };
void *pool;
- u32 pool_index = parts.pool_index - 1;
+ u32 pool_index = parts.pool_index_plus_1 - 1;
size_t offset = parts.offset << DEPOT_STACK_ALIGN;
struct stack_record *stack;
_
Patches currently in -mm which might be from pcc@xxxxxxxxxx are
stackdepot-rename-pool_index-to-pool_index_plus_1.patch
