[PATCH net-next] net/smc: Allow SMC-D 1MB DMB allocations
From: Guvenc Gulce <hidden>
Date: 2021-08-09 08:10:29
Also in:
linux-s390
Subsystem:
networking [general], shared memory communications (smc) sockets, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, D. Wythe, Dust Li, Sidraya Jayagond, Wenjia Zhang, Linus Torvalds
From: Stefan Raspl <redacted>
Commit a3fe3d01bd0d7 ("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 <redacted>
Signed-off-by: Guvenc Gulce <redacted>
---
net/smc/smc_core.c | 31 ++++++++++++++++---------------
1 file changed, 16 insertions(+), 15 deletions(-)
diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index cd0d7c908b2a..edc8962364f3 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c@@ -1752,21 +1752,30 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini) 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 @@ static int smcr_buf_map_usable_links(struct smc_link_group *lgr, 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);
--
2.25.1