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net/smc: Allow SMC-D 1MB DMB allocations 

Commit a3fe3d01bd ("net/smc: introduce sg-logic for RMBs") introduced
a restriction for RMB allocations as used by SMC-R. However, SMC-D does
not use scatter-gather lists to back its DMBs, yet it was limited by
this restriction, still.
This patch exempts SMC, but limits allocations to the maximum RMB/DMB
size respectively.

Signed-off-by: Stefan Raspl <raspl@linux.ibm.com>
Signed-off-by: Guvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stefan Raspl 2021-08-09 10:10:14 +02:00 committed by David S. Miller
parent 919d13a7e4
commit 67161779a9
1 changed files with 16 additions and 15 deletions
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31
net/smc/smc_core.c
View File

@ -1752,21 +1752,30 @@ out:
return rc;
}
/* convert the RMB size into the compressed notation - minimum 16K.
#define SMCD_DMBE_SIZES 6 /* 0 -> 16KB, 1 -> 32KB, .. 6 -> 1MB */
#define SMCR_RMBE_SIZES 5 /* 0 -> 16KB, 1 -> 32KB, .. 5 -> 512KB */
/* convert the RMB size into the compressed notation (minimum 16K, see
* SMCD/R_DMBE_SIZES.
* In contrast to plain ilog2, this rounds towards the next power of 2,
* so the socket application gets at least its desired sndbuf / rcvbuf size.
*/
static u8 smc_compress_bufsize(int size)
static u8 smc_compress_bufsize(int size, bool is_smcd, bool is_rmb)
{
const unsigned int max_scat = SG_MAX_SINGLE_ALLOC * PAGE_SIZE;
u8 compressed;
if (size <= SMC_BUF_MIN_SIZE)
return 0;
size = (size - 1) >> 14;
compressed = ilog2(size) + 1;
if (compressed >= SMC_RMBE_SIZES)
compressed = SMC_RMBE_SIZES - 1;
size = (size - 1) >> 14; /* convert to 16K multiple */
compressed = min_t(u8, ilog2(size) + 1,
is_smcd ? SMCD_DMBE_SIZES : SMCR_RMBE_SIZES);
if (!is_smcd && is_rmb)
/* RMBs are backed by & limited to max size of scatterlists */
compressed = min_t(u8, compressed, ilog2(max_scat >> 14));
return compressed;
}
@ -1982,17 +1991,12 @@ out:
return rc;
}
#define SMCD_DMBE_SIZES 6 /* 0 -> 16KB, 1 -> 32KB, .. 6 -> 1MB */
static struct smc_buf_desc *smcd_new_buf_create(struct smc_link_group *lgr,
bool is_dmb, int bufsize)
{
struct smc_buf_desc *buf_desc;
int rc;
if (smc_compress_bufsize(bufsize) > SMCD_DMBE_SIZES)
return ERR_PTR(-EAGAIN);
/* try to alloc a new DMB */
buf_desc = kzalloc(sizeof(*buf_desc), GFP_KERNEL);
if (!buf_desc)
@ -2041,9 +2045,8 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb)
/* use socket send buffer size (w/o overhead) as start value */
sk_buf_size = smc->sk.sk_sndbuf / 2;
for (bufsize_short = smc_compress_bufsize(sk_buf_size);
for (bufsize_short = smc_compress_bufsize(sk_buf_size, is_smcd, is_rmb);
bufsize_short >= 0; bufsize_short--) {
if (is_rmb) {
lock = &lgr->rmbs_lock;
buf_list = &lgr->rmbs[bufsize_short];
@ -2052,8 +2055,6 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb)
buf_list = &lgr->sndbufs[bufsize_short];
}
bufsize = smc_uncompress_bufsize(bufsize_short);
if ((1 << get_order(bufsize)) > SG_MAX_SINGLE_ALLOC)
continue;
/* check for reusable slot in the link group */
buf_desc = smc_buf_get_slot(bufsize_short, lock, buf_list);