Commit c180188e authored by Jiri Slaby (SUSE)'s avatar Jiri Slaby (SUSE) Committed by Jakub Kicinski
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net: set the minimum for net_hotdata.netdev_budget_usecs 



Commit 7acf8a1e ("Replace 2 jiffies with sysctl netdev_budget_usecs
to enable softirq tuning") added a possibility to set
net_hotdata.netdev_budget_usecs, but added no lower bound checking.

Commit a4837980 ("net: revert default NAPI poll timeout to 2 jiffies")
made the *initial* value HZ-dependent, so the initial value is at least
2 jiffies even for lower HZ values (2 ms for 1000 Hz, 8ms for 250 Hz, 20
ms for 100 Hz).

But a user still can set improper values by a sysctl. Set .extra1
(the lower bound) for net_hotdata.netdev_budget_usecs to the same value
as in the latter commit. That is to 2 jiffies.

Fixes: a4837980 ("net: revert default NAPI poll timeout to 2 jiffies")
Fixes: 7acf8a1e ("Replace 2 jiffies with sysctl netdev_budget_usecs to enable softirq tuning")
Signed-off-by: default avatarJiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Dmitry Yakunin <zeil@yandex-team.ru>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Link: https://patch.msgid.link/20250220110752.137639-1-jirislaby@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 0e4427f8

net/core/sysctl_net_core.c

+2 −1
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ static int min_sndbuf = SOCK_MIN_SNDBUF; 
static int min_rcvbuf = SOCK_MIN_RCVBUF;

static int max_skb_frags = MAX_SKB_FRAGS;

static int min_mem_pcpu_rsv = SK_MEMORY_PCPU_RESERVE;

static int netdev_budget_usecs_min = 2 * USEC_PER_SEC / HZ;



static int net_msg_warn;	/* Unused, but still a sysctl */
@@ -587,7 +588,7 @@ static struct ctl_table net_core_table[] = { 
		.maxlen		= sizeof(unsigned int),

		.mode		= 0644,

		.proc_handler	= proc_dointvec_minmax,

		.extra1		= SYSCTL_ZERO,

		.extra1		= &netdev_budget_usecs_min,

	},

	{

		.procname	= "fb_tunnels_only_for_init_net",