在 2025/8/12 22:31, Dan Carpenter 写道:
On Tue, Aug 12, 2025 at 10:13:43PM +0800, Qianfeng Rong wrote:
在 2025/8/12 21:48, Dan Carpenter 写道:
On Tue, Aug 12, 2025 at 09:32:18PM +0800, Qianfeng Rong wrote:
Remove array_size() calls and replace vmalloc() with vmalloc_array() to
simplify the code.
Signed-off-by: Qianfeng Rong <rongqianfeng@xxxxxxxx>
---
drivers/net/wireless/marvell/mwifiex/cfg80211.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/marvell/mwifiex/cfg80211.c b/drivers/net/wireless/marvell/mwifiex/cfg80211.c
index 3498743d5ec0..fb4183ff02a9 100644
--- a/drivers/net/wireless/marvell/mwifiex/cfg80211.c
+++ b/drivers/net/wireless/marvell/mwifiex/cfg80211.c
@@ -4673,8 +4673,8 @@ int mwifiex_init_channel_scan_gap(struct mwifiex_adapter *adapter)
* additional active scan request for hidden SSIDs on passive channels.
*/
adapter->num_in_chan_stats = 2 * (n_channels_bg + n_channels_a);
- adapter->chan_stats = vmalloc(array_size(sizeof(*adapter->chan_stats),
- adapter->num_in_chan_stats));
+ adapter->chan_stats = vmalloc_array(adapter->num_in_chan_stats,
+ sizeof(*adapter->chan_stats));
n_channels_bg is 14
n_channels_a is either 0 or 31 depending on if we're using BAND_A.
sizeof(*adapter->chan_stats) is 10.
So we're either allocating 280 or 900 bytes, which is quite small. We
should just use kmalloc_array() instead of vmalloc_array().
Switching to kmalloc_array() requires changing vfree() to kfree(),
but I couldn't locate the memory release code.
It's not hard to locate with a bit of looking. ;)
Yes, I did find it. ;)
This modification
likely requires deep familiarity with the codebase. Also, for
variable-sized allocations, kvmalloc_array() is preferable, but
requires kvfree() for proper memory release.
Don't use kvmalloc_array(). The rules are:
1) small amounts of memory: kmalloc()
2) possibly large ammounts of memory up to 2GB: kvmalloc()
3) definitely large ammounts of memory or larger than 2GB: vmalloc()
Allocations under 8 pages should use kmalloc() for efficiency. For
allocations exceeding 8 pages, kvmalloc() or vmalloc() is preferable
(of course, non-contiguous physical memory can be used) since
kernel memory management defines PAGE_ALLOC_COSTLY_ORDER = 3
(indicating 8 pages), beyond which contiguous physical memory
allocation becomes unreliable and costly.
There are also places where the memory needs to be contiguous and for
those situations kvmalloc() and vmalloc() can't be used.
Here we're allocating less than a PAGE so the appropriate thing is
kmalloc_array().
I'm looking at this some more and these statistics are updated in
mwifiex_update_chan_statistics() and not necessarily all of them
are updated. But they're used in mwifiex_cfg80211_dump_survey()
when potentially the memory is still uninitialized.
I really think we should zero this memory, so lets allocate it
with kcalloc().
I agree with you, I will try to do this in the next version.
regards,
dan carpenter
