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Revision 16b34aa44b257155d9392a19e08e4ce139bc2789 authored by Ronnie Sahlberg on 08 March 2019, 02:58:21 UTC, committed by Steve French on 15 March 2019, 00:32:35 UTC 
cifs: prevent starvation in wait_for_free_credits for multi-credit requests
 
Reserve the last MAX_COMPOUND credits for any request asking for >1 credit.
This is to prevent future compound requests from becoming starved while waiting
for potentially many requests is there is a large number of concurrent
singe-credit requests.

However, we need to protect from servers that are very slow to hand out
new credits on new sessions so we only do this IFF there are 2*MAX_COMPOUND
(arbitrary) credits already in flight.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
1 parent b227d21
Raw File
nodemask.c 
// SPDX-License-Identifier: GPL-2.0
#include <linux/nodemask.h>
#include <linux/module.h>
#include <linux/random.h>

int __next_node_in(int node, const nodemask_t *srcp)
{
	int ret = __next_node(node, srcp);

	if (ret == MAX_NUMNODES)
		ret = __first_node(srcp);
	return ret;
}
EXPORT_SYMBOL(__next_node_in);

#ifdef CONFIG_NUMA
/*
 * Return the bit number of a random bit set in the nodemask.
 * (returns NUMA_NO_NODE if nodemask is empty)
 */
int node_random(const nodemask_t *maskp)
{
	int w, bit = NUMA_NO_NODE;

	w = nodes_weight(*maskp);
	if (w)
		bit = bitmap_ord_to_pos(maskp->bits,
			get_random_int() % w, MAX_NUMNODES);
	return bit;
}
#endif
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