lkml.org 
[lkml]   [2020]   [Oct]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH v2][next] x86/uv/time: Replace one-element array and save heap space
There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

struct uv_rtc_timer_head contains a one-element array cpu[1].

Switch it to a flexible array and use the struct_size() helper to
calculate the allocation size. Also, save some heap space in the
process[3].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arrays
[3] https://lore.kernel.org/lkml/20200518190114.GA7757@embeddedor/

Reviewed-by: Kees Cook <keescook@chromium.org>
Build-tested-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/5f75bc0a.rQcNS6620b2eA74S%25lkp@intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
Changes in v2:
- Modify changelog text (Thomas).
- Add Reviewed-by and Build-tested-by tags.
- Add a public link to the build-test results.

arch/x86/platform/uv/uv_time.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/x86/platform/uv/uv_time.c b/arch/x86/platform/uv/uv_time.c
index f82a1337a608..6c348c2d0def 100644
--- a/arch/x86/platform/uv/uv_time.c
+++ b/arch/x86/platform/uv/uv_time.c
@@ -52,7 +52,7 @@ struct uv_rtc_timer_head {
struct {
int lcpu; /* systemwide logical cpu number */
u64 expires; /* next timer expiration for this cpu */
- } cpu[1];
+ } cpu[];
};

/*
@@ -148,9 +148,8 @@ static __init int uv_rtc_allocate_timers(void)
struct uv_rtc_timer_head *head = blade_info[bid];

if (!head) {
- head = kmalloc_node(sizeof(struct uv_rtc_timer_head) +
- (uv_blade_nr_possible_cpus(bid) *
- 2 * sizeof(u64)),
+ head = kmalloc_node(struct_size(head, cpu,
+ uv_blade_nr_possible_cpus(bid)),
GFP_KERNEL, nid);
if (!head) {
uv_rtc_deallocate_timers();
--
2.27.0
\
 
 \ /
  Last update: 2020-10-01 16:51    [W:0.051 / U:0.824 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site