[PATCH] um: vector: Reduce stack usage in vector_eth_configure()
Tiwei Bie
tiwei.btw at antgroup.com
Mon Jun 23 04:08:29 PDT 2025
When compiling with clang (19.1.7), initializing *vp using a compound
literal may result in excessive stack usage. Fix it by initializing the
required fields of *vp individually.
Without this patch:
$ objdump -d arch/um/drivers/vector_kern.o | ./scripts/checkstack.pl x86_64 0
...
0x0000000000000540 vector_eth_configure [vector_kern.o]:1472
...
With this patch:
$ objdump -d arch/um/drivers/vector_kern.o | ./scripts/checkstack.pl x86_64 0
...
0x0000000000000540 vector_eth_configure [vector_kern.o]:208
...
Reported-by: kernel test robot <lkp at intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202506221017.WtB7Usua-lkp@intel.com/
Signed-off-by: Tiwei Bie <tiwei.btw at antgroup.com>
---
arch/um/drivers/vector_kern.c | 42 +++++++++++------------------------
1 file changed, 13 insertions(+), 29 deletions(-)
diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
index f292e0b4ff8b..9bbbddfe866b 100644
--- a/arch/um/drivers/vector_kern.c
+++ b/arch/um/drivers/vector_kern.c
@@ -1625,35 +1625,19 @@ static void vector_eth_configure(
device->dev = dev;
- *vp = ((struct vector_private)
- {
- .list = LIST_HEAD_INIT(vp->list),
- .dev = dev,
- .unit = n,
- .options = get_transport_options(def),
- .rx_irq = 0,
- .tx_irq = 0,
- .parsed = def,
- .max_packet = get_mtu(def) + ETH_HEADER_OTHER,
- /* TODO - we need to calculate headroom so that ip header
- * is 16 byte aligned all the time
- */
- .headroom = get_headroom(def),
- .form_header = NULL,
- .verify_header = NULL,
- .header_rxbuffer = NULL,
- .header_txbuffer = NULL,
- .header_size = 0,
- .rx_header_size = 0,
- .rexmit_scheduled = false,
- .opened = false,
- .transport_data = NULL,
- .in_write_poll = false,
- .coalesce = 2,
- .req_size = get_req_size(def),
- .in_error = false,
- .bpf = NULL
- });
+ INIT_LIST_HEAD(&vp->list);
+ vp->dev = dev;
+ vp->unit = n;
+ vp->options = get_transport_options(def);
+ vp->parsed = def;
+ vp->max_packet = get_mtu(def) + ETH_HEADER_OTHER;
+ /*
+ * TODO - we need to calculate headroom so that ip header
+ * is 16 byte aligned all the time
+ */
+ vp->headroom = get_headroom(def);
+ vp->coalesce = 2;
+ vp->req_size = get_req_size(def);
dev->features = dev->hw_features = (NETIF_F_SG | NETIF_F_FRAGLIST);
INIT_WORK(&vp->reset_tx, vector_reset_tx);
--
2.34.1
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