On 25/03/2024 14:21, Jason Yan wrote:
On 2024/3/25 22:03, Damien Le Moal wrote:
On 3/25/24 22:17, Yihang Li wrote:
This series [1] reducing the kmalloc() minimum alignment on arm64 to 8
(from 128).
And ? What is the point you are trying to convey here ?
The hisi_sas has special requirements on the memory address alignment
(must be 16-byte-aligned) of the command request frame, so add a SMP
request allocation callback and fill it in for the hisi_sas driver.
128 is aligned to 16. So what is the problem you are trying to solve
here ?
Can you clarify ? I suspect this is all about memory allocation
optimization ?
After series [1] been merged, kmalloc is 8-byte-aligned, however
hisi_sas hardware needs 16-byte-aligned. That's the problem.
Link:
https://urldefense.com/v3/__https://lkml.kernel.org/r/20230612153201.554742-1-catalin.marinas@arm.com__;!!ACWV5N9M2RV99hQ!L85qzmByNbkBbZByXKuNMAhvt8wxKPCsogKt3Pgn93DTkzfc54jA3of5XL8oEDDDDTMU1OtghdKiLZdKe5ub$ ; [1]
Signed-off-by: Yihang Li <liyihang9@xxxxxxxxxx>
---
drivers/scsi/hisi_sas/hisi_sas_main.c | 14 ++++++++++++
drivers/scsi/libsas/sas_expander.c | 31 ++++++++++++++++++---------
include/scsi/libsas.h | 3 +++
3 files changed, 38 insertions(+), 10 deletions(-)
diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c
b/drivers/scsi/hisi_sas/hisi_sas_main.c
index 097dfe4b620d..40329558d435 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_main.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
@@ -2031,6 +2031,19 @@ static int hisi_sas_write_gpio(struct
sas_ha_struct *sha, u8 reg_type,
reg_index, reg_count, write_data);
}
+static void *hisi_sas_alloc_smp_req(int size)
+{
+ u8 *p;
+
+ /* The address must be 16-byte-aligned. */
ARCH_DMA_MINALIGN is not always 16, right ?
+ size = ALIGN(size, ARCH_DMA_MINALIGN);
+ p = kzalloc(size, GFP_KERNEL);
Please make it clear that kmalloc() will return a naturally-aligned
memory for power-of-2 sizes, and so ensuring that size is roundup to 16B
will give a data which is aligned to 16B
+ if (p)
+ p[0] = SMP_REQUEST;
+
+ return p;
+}
+
static void hisi_sas_phy_disconnected(struct hisi_sas_phy *phy)
{
struct asd_sas_phy *sas_phy = &phy->sas_phy;
@@ -2130,6 +2143,7 @@ static struct sas_domain_function_template
hisi_sas_transport_ops = {
.lldd_write_gpio = hisi_sas_write_gpio,
.lldd_tmf_aborted = hisi_sas_tmf_aborted,
.lldd_abort_timeout = hisi_sas_internal_abort_timeout,
+ .lldd_alloc_smp_req = hisi_sas_alloc_smp_req,
Why this complexity ? Why not simply modify alloc_smp_req() to have
the required
alignment ? This will avoid a costly indirect function call.
Yeah, I think it's simpler to modify alloc_smp_req() directly too.
Yihang, Can you please cook a new one?
Thansk,
Jason
