diff mbox series

[4/5] octeontx2-af: Fix the size of memory allocated for the 'id_bmap' bitmap

Message ID ce2710771939065d68f95d86a27cf7cea7966365.1669378798.git.christophe.jaillet@wanadoo.fr (mailing list archive)
State Accepted
Commit 6d135d9e2b004024b84bd7c308f58300b64d29b6
Delegated to: Netdev Maintainers
Headers show
Series [1/5] octeontx2-af: Fix a potentially spurious error message | expand

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Context Check Description
netdev/tree_selection success Guessed tree name to be net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix warning Target tree name not specified in the subject
netdev/cover_letter warning Series does not have a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers success CCed 11 of 11 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 10 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Christophe JAILLET Nov. 25, 2022, 12:24 p.m. UTC
This allocation is really spurious.
The size of the bitmap is 'tot_ids' and it is used as such in the driver.

So we could expect something like:
   table->id_bmap = devm_kcalloc(rvu->dev, BITS_TO_LONGS(table->tot_ids),
			         sizeof(long), GFP_KERNEL);

However, when the bitmap is allocated, we allocate:
   BITS_TO_LONGS(table->tot_ids) * table->tot_ids ~=
   table->tot_ids / 32 * table->tot_ids ~=
   table->tot_ids^2 / 32

It is proportional to the square of 'table->tot_ids' which seems to
potentially be big.

Allocate the expected amount of memory, and switch to the bitmap API to
have it more straightforward.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
This patch is speculative.

If I'm right, I'm curious to know if 'able->tot_ids' can really get big
(I'm just guessing) , and if yes, how much.
---
 drivers/net/ethernet/marvell/octeontx2/af/rvu_npc_hash.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_npc_hash.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_npc_hash.c
index 3f94b620ef5a..ae34746341c4 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_npc_hash.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_npc_hash.c
@@ -1914,8 +1914,8 @@  int rvu_npc_exact_init(struct rvu *rvu)
 	dev_dbg(rvu->dev, "%s: Allocated bitmap for 32 entry cam\n", __func__);
 
 	table->tot_ids = (table->mem_table.depth * table->mem_table.ways) + table->cam_table.depth;
-	table->id_bmap = devm_kcalloc(rvu->dev, BITS_TO_LONGS(table->tot_ids),
-				      table->tot_ids, GFP_KERNEL);
+	table->id_bmap = devm_bitmap_zalloc(rvu->dev, table->tot_ids,
+					    GFP_KERNEL);
 
 	if (!table->id_bmap)
 		return -ENOMEM;