On 1/26/24 01:27, Bernard Metzler wrote:
-----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?
The warning still appears with KASAN enabled from my side.
I am sure we do not want to optimize the driver for building with KASAN
debug options enabled.
Agreed.
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.
I am not sure about it after check the relevant bugzilla, maybe the reporter
can verify it.
Thanks,
Guoqing
