Commit 67161779 authored by Stefan Raspl's avatar Stefan Raspl Committed by David S. Miller
Browse files

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



Commit a3fe3d01 ("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: default avatarStefan Raspl <raspl@linux.ibm.com>
Signed-off-by: default avatarGuvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 919d13a7

net/smc/smc_core.c

+16 −15
Original line number Diff line number Diff line
@@ -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);