Hi, James, I think I found the root cause: lpfc's device memory doesn't support 128bit load/store. But Loongson-3's optimised memcpy() will use 128bit load/store instructions (gslq/gssq). So is this patch neccesory to avoid 128bit memory access (maybe there are other platforms have the same problem)? Huacai ------------------ Original ------------------ From: "James Smart"<[email protected]>; Date: Mon, Mar 5, 2018 11:37 PM To: "陈华才"<[email protected]>; "Dick Kennedy"<[email protected]>; Cc: "James E . J . Bottomley"<[email protected]>; "Martin K . Petersen"<[email protected]>; "Fuxin Zhang"<[email protected]>; "linux-scsi"<[email protected]>; "stable"<[email protected]>; Subject: Re: [PATCH] scsi: lpfc: Switch memcpy_fromio() to __read32_copy()
On 3/4/2018 10:56 PM, 陈华才 wrote: > No one has the same problem? Or this patch need improve? > > Huacai > > ------------------ Original ------------------ > From: "陈华才"<[email protected]>; > Date: Thu, Mar 1, 2018 01:59 PM > To: "James Smart"<[email protected]>; "Dick > Kennedy"<[email protected]>; > Cc: "James E . J . Bottomley"<[email protected]>; "Martin K . > Petersen"<[email protected]>; "Fuxin Zhang"<[email protected]>; > "linux-scsi"<[email protected]>; "stable"<[email protected]>; > Subject: Re:[PATCH] scsi: lpfc: Switch memcpy_fromio() to __read32_copy() > > Ping? > > ------------------ Original ------------------ > From: "Huacai Chen"<[email protected]>; > Date: Fri, Jan 26, 2018 08:53 PM > To: "James Smart"<[email protected]>; "Dick > Kennedy"<[email protected]>; > Cc: "James E . J . Bottomley"<[email protected]>; "Martin K . > Petersen"<[email protected]>; "Fuxin Zhang"<[email protected]>; > "linux-scsi"<[email protected]>; "Huacai Chen"<[email protected]>; > "stable"<[email protected]>; > Subject: [PATCH] scsi: lpfc: Switch memcpy_fromio() to __read32_copy() > > In commit bc73905abf770192 ("[SCSI] lpfc 8.3.16: SLI Additions, updates, > and code cleanup"), lpfc_memcpy_to_slim() have switched memcpy_toio() to > __write32_copy() in order to prevent unaligned 64 bit copy. Recently, we > found that lpfc_memcpy_from_slim() have similar issues, so let it switch > memcpy_fromio() to __read32_copy(). > > Cc: [email protected] > Signed-off-by: Huacai Chen <[email protected]> > --- > drivers/scsi/lpfc/lpfc_compat.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/lpfc/lpfc_compat.h b/drivers/scsi/lpfc/lpfc_compat.h > index 6b32b0a..47d4fad 100644 > --- a/drivers/scsi/lpfc/lpfc_compat.h > +++ b/drivers/scsi/lpfc/lpfc_compat.h > @@ -91,8 +91,8 @@ lpfc_memcpy_to_slim( void __iomem *dest, void *src, > unsigned int bytes) > static inline void > lpfc_memcpy_from_slim( void *dest, void __iomem *src, unsigned int bytes) > { > - /* actually returns 1 byte past dest */ > - memcpy_fromio( dest, src, bytes); > + /* convert bytes in argument list to word count for copy function */ > + __ioread32_copy(dest, src, bytes / sizeof(uint32_t)); > } > > #endif /* __BIG_ENDIAN */ Huacai, Note: the original change was 7 yrs ago and we've had no reports of issues. but.... This change didn't look necessary as the memcpy_XXXio() should allow byte alignments and byte-based lengths. Which means the original patch also wasn't necessary, which implies that the platform that had the issues has an api restriction not normally found on the other platforms. I have no problem with the change though. -- james Signed-off-by: James Smart <[email protected]>
