This is a note to let you know that I've just added the patch titled
net/smc: Allow SMC-D 1MB DMB allocations
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-smc-allow-smc-d-1mb-dmb-allocations.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 331ab7774f5b71d339461740db9db8a2c4e3d8d8
Author: Stefan Raspl <raspl@xxxxxxxxxxxxx>
Date: Mon Aug 9 10:10:14 2021 +0200
net/smc: Allow SMC-D 1MB DMB allocations
[ Upstream commit 67161779a9ea926fccee8de047ae66cbd3482b91 ]
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 <raspl@xxxxxxxxxxxxx>
Signed-off-by: Guvenc Gulce <guvenc@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Stable-dep-of: 3ac14b9dfbd3 ("net/smc: set rmb's SG_MAX_SINGLE_ALLOC limitation only when CONFIG_ARCH_NO_SG_CHAIN is defined")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index ab9ecdd1af0ac..701bfc2bab239 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -1375,21 +1375,30 @@ 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;
}
@@ -1608,17 +1617,12 @@ 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)
@@ -1666,9 +1670,8 @@ 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];
@@ -1677,8 +1680,6 @@ 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);
