On 26/03/2024 13:14, Damien Le Moal wrote:
On 3/26/24 21:43, Yihang Li wrote:
This series [1] reducing the kmalloc() minimum alignment on arm64 to 8
(from 128). In libsas, this will cause SMP requests to be 8-byte-aligned
through kmalloc() allocation. However, for the hisi_sas hardware, all
commands address must be 16-byte-aligned.
Otherwise, the commands fail to
be executed.
ARCH_DMA_MINALIGN represents the minimum (static) alignment for safe DMA
operations, so use ARCH_DMA_MINALIGN as the alignment for SMP request.
Link: https://lkml.kernel.org/r/20230612153201.554742-1-catalin.marinas@xxxxxxx [1]
Signed-off-by: Yihang Li <liyihang9@xxxxxxxxxx>
---
Changes since v1:
- Directly modify alloc_smp_req() instead of using handler callback.
---
drivers/scsi/libsas/sas_expander.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index a2204674b680..941abc7298df 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -135,7 +135,10 @@ static int smp_execute_task(struct domain_device *dev, void *req, int req_size,
static inline void *alloc_smp_req(int size)
{
- u8 *p = kzalloc(size, GFP_KERNEL);
+ u8 *p;
+
+ size = ALIGN(size, ARCH_DMA_MINALIGN);
If this is a hisi_sas requirement, then why use ARCH_DMA_MINALIGN and
not 16B as minimum alignment?
Or are we really talking about an arch requirement?
+ p = kzalloc(size, GFP_KERNEL);
Nit: why not:
p = kzalloc(ALIGN(size, ARCH_DMA_MINALIGN), GFP_KERNEL);
if (p)
p[0] = SMP_REQUEST;
return p;
Otherwise looks OK to me.
John,
Unrelated to this patch, but I wonder if the GFP_KERNEL used here shouldn't be
GFP_NOIO... Is this ever called in the IO path or error recovery ?
These should not be called in the IO path - as they are management
functions. But I am quite confident that they can be called in SCSI
error handling (for libsas).
Thanks,
John
