> -----Original Message----- > From: Guoqing Jiang <guoqing.jiang@xxxxxxxxx> > Sent: Thursday, January 25, 2024 1:15 AM > To: Bernard Metzler <BMT@xxxxxxxxxxxxxx>; linux-rdma@xxxxxxxxxxxxxxx > Cc: jgg@xxxxxxxx; leon@xxxxxxxxxx; ionut_n2001@xxxxxxxxx > Subject: [EXTERNAL] Re: [PATCH] RDMA/siw: Trim size of page array to max > size needed > > Hi Bernard, > > On 1/25/24 03:59, Bernard Metzler wrote: > >> -----Original Message----- > >> From: Guoqing Jiang <guoqing.jiang@xxxxxxxxx> > >> Sent: Tuesday, January 23, 2024 3:43 AM > >> To: Bernard Metzler <BMT@xxxxxxxxxxxxxx>; linux-rdma@xxxxxxxxxxxxxxx > >> Cc: jgg@xxxxxxxx; leon@xxxxxxxxxx; ionut_n2001@xxxxxxxxx > >> Subject: [EXTERNAL] Re: [PATCH] RDMA/siw: Trim size of page array to > max > >> size needed > >> > >> Hi Bernard, > >> > >> On 1/19/24 21:05, Bernard Metzler wrote: > >>> siw tries sending all parts of an iWarp wire frame in one socket > >>> send operation. If user data can be send without copy, user data > >>> pages for one wire frame are referenced in an fixed size page array. > >>> The size of this array can be made 2 elements smaller, since it > >>> does not reference iWarp header and trailer crc. Trimming > >>> the page array reduces the affected siw_tx_hdt() functions frame > >>> size, staying below 1024 bytes. This avoids the following > >>> compile-time warning: > >>> > >>> drivers/infiniband/sw/siw/siw_qp_tx.c: In function 'siw_tx_hdt': > >>> drivers/infiniband/sw/siw/siw_qp_tx.c:677:1: warning: the frame > >>> size of 1040 bytes is larger than 1024 bytes [-Wframe-larger- > than=] > >> I saw similar warning in my ubuntu 22.04 VM which has below gcc. > >> > >> root@buk:/home/gjiang/linux-mirror# make M=drivers/infiniband/sw/siw/ > >> -j16 W=1 > >> CC [M] drivers/infiniband/sw/siw/siw_qp_tx.o > >> drivers/infiniband/sw/siw/siw_qp_tx.c: In function ‘siw_tx_hdt’: > >> drivers/infiniband/sw/siw/siw_qp_tx.c:665:1: warning: the frame size > of > >> 1440 bytes is larger than 1024 bytes [-Wframe-larger-than=] > >> 665 | } > >> | ^ > >> > > Whew.. that is quite substantially off the target! > > How come different compilers making so much of a difference. > > Guoqing, can you check if the macro computing the maximum number > > of fragments is broken, i.e., computes different values in > > the cases you refer? > > Sorry, I was wrong 😅. > > The warning is not relevant with compiler, and it also appears with gcc- > 13.1 > after enable KASAN which is used to find out-of-bounds bugs. Also, there > are lots of -Wframe-larger-than warning from other places as well. > > > Thanks a lot! > > Bernard > >> # gcc --version > >> gcc (Ubuntu 12.3.0-1ubuntu1~22.04) 12.3.0 > >> > >> And it still appears after apply this patch on top of 6.8-rc1. > >> > >> root@buk:/home/gjiang/linux-mirror# git am > >> > ./20240119_bmt_rdma_siw_trim_size_of_page_array_to_max_size_needed.mbx > >> Applying: RDMA/siw: Trim size of page array to max size needed > >> root@buk:/home/gjiang/linux-mirror# make M=drivers/infiniband/sw/siw/ > >> -j16 W=1 > >> CC [M] drivers/infiniband/sw/siw/siw_qp_tx.o > >> drivers/infiniband/sw/siw/siw_qp_tx.c: In function ‘siw_tx_hdt’: > >> drivers/infiniband/sw/siw/siw_qp_tx.c:668:1: warning: the frame size > of > >> 1408 bytes is larger than 1024 bytes [-Wframe-larger-than=] > >> 668 | } > >> | ^ > > The patch actually reduced the frame size from 1440 to 1408 though it is > still larger than 1024. > So in your opinion, does this patch fix the issue of having a frame size larger than 1024 bytes for a typical build? I am sure we do not want to optimize the driver for building with KASAN debug options enabled. The original bug report claimed a frame size of 1040 bytes for a build w/o KASAN, being larger than 1024 bytes by 16 bytes. I think this patch fixes the reported issue. Thanks a lot, Bernard. > Thanks, > Guoqing
