From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug alb_break_llc() decides whether to break LLC preference during active load balance. It does so by testing that every runnable fair task on the source rq prefers its LLC: env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable But the two counters cover different sets. nr_pref_llc_running is updated in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued, so it follows queued tasks. h_nr_runnable is updated in set_delayed()/ clear_delayed() and drops delay-dequeued tasks. So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks, alb_break_llc() returns false, and active balance is free to pull a task off its preferred LLC. Active balance only moves runnable tasks, and this is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB skips the per-task test in can_migrate_task(). The runnable set is the one we want. Fix it on the counter side. A task should be counted in nr_pref_llc_running exactly while it is both queued on its preferred LLC (pref_llc_queued) and runnable (!sched_delayed). Define that membership once in task_pref_llc_runnable(), and adjust the counter only through pref_llc_running_inc()/pref_llc_running_dec() from the four sites that change either input: account_llc_enqueue(), account_llc_dequeue(), set_delayed() and clear_delayed(). Gating every update on the same predicate keeps the delay, wake and dequeue paths from double-counting or underflowing; see the comments at those sites for the ordering. nr_llc_running and sd->llc_counts are not touched and stay on queued semantics. Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC") Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/ Reported-by: Zhan Xusheng Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- net/dsa/Kconfig | 230 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 230 insertions(+) create mode 100644 net/dsa/Kconfig (limited to 'net/dsa/Kconfig') diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig new file mode 100644 index 000000000..23b4b7400 --- /dev/null +++ b/net/dsa/Kconfig @@ -0,0 +1,230 @@ +# SPDX-License-Identifier: GPL-2.0-only + +menuconfig NET_DSA + tristate "Distributed Switch Architecture" + depends on BRIDGE || BRIDGE=n + depends on HSR || HSR=n + depends on INET && NETDEVICES + select GRO_CELLS + select NET_SWITCHDEV + select PHYLINK + select NET_DEVLINK + imply NET_SELFTESTS + help + Say Y if you want to enable support for the hardware switches supported + by the Distributed Switch Architecture. + +if NET_DSA + +# Drivers must select the appropriate tagging format(s) + +config NET_DSA_TAG_NONE + tristate "No-op tag driver" + help + Say Y or M if you want to enable support for switches which don't tag + frames over the CPU port. + +config NET_DSA_TAG_AR9331 + tristate "Tag driver for Atheros AR9331 SoC with built-in switch" + help + Say Y or M if you want to enable support for tagging frames for + the Atheros AR9331 SoC with built-in switch. + +config NET_DSA_TAG_BRCM_COMMON + tristate + default n + +config NET_DSA_TAG_BRCM + tristate "Tag driver for Broadcom switches using in-frame headers" + select NET_DSA_TAG_BRCM_COMMON + help + Say Y if you want to enable support for tagging frames for the + Broadcom switches which place the tag after the MAC source address. + +config NET_DSA_TAG_BRCM_LEGACY + tristate "Tag driver for BCM63xx legacy switches using in-frame headers" + select NET_DSA_TAG_BRCM_COMMON + help + Say Y if you want to enable support for tagging frames for the + BCM63xx legacy switches which place the tag after the MAC source + address. + This tag is used in BCM63xx legacy switches which work without the + original FCS and length before the tag insertion. + +config NET_DSA_TAG_BRCM_LEGACY_FCS + tristate "Tag driver for BCM53xx legacy switches using in-frame headers" + select NET_DSA_TAG_BRCM_COMMON + help + Say Y if you want to enable support for tagging frames for the + BCM53xx legacy switches which place the tag after the MAC source + address. + This tag is used in BCM53xx legacy switches which expect original + FCS and length before the tag insertion to be present. + +config NET_DSA_TAG_BRCM_PREPEND + tristate "Tag driver for Broadcom switches using prepended headers" + select NET_DSA_TAG_BRCM_COMMON + help + Say Y if you want to enable support for tagging frames for the + Broadcom switches which places the tag before the Ethernet header + (prepended). + +config NET_DSA_TAG_HELLCREEK + tristate "Tag driver for Hirschmann Hellcreek TSN switches" + help + Say Y or M if you want to enable support for tagging frames + for the Hirschmann Hellcreek TSN switches. + +config NET_DSA_TAG_GSWIP + tristate "Tag driver for Lantiq / Intel GSWIP switches" + help + Say Y or M if you want to enable support for tagging frames for the + Lantiq / Intel GSWIP switches. + +config NET_DSA_TAG_DSA_COMMON + tristate + +config NET_DSA_TAG_DSA + tristate "Tag driver for Marvell switches using DSA headers" + select NET_DSA_TAG_DSA_COMMON + help + Say Y or M if you want to enable support for tagging frames for the + Marvell switches which use DSA headers. + +config NET_DSA_TAG_EDSA + tristate "Tag driver for Marvell switches using EtherType DSA headers" + select NET_DSA_TAG_DSA_COMMON + help + Say Y or M if you want to enable support for tagging frames for the + Marvell switches which use EtherType DSA headers. + +config NET_DSA_TAG_MT7628 + tristate "Tag driver for the MT7628 embedded switch" + help + Say Y or M if you want to enable support for tagging frames for the + switch embedded in the MT7628 SoC. + +config NET_DSA_TAG_MTK + tristate "Tag driver for Mediatek switches" + help + Say Y or M if you want to enable support for tagging frames for + Mediatek switches. + +config NET_DSA_TAG_MXL_862XX + tristate "Tag driver for MaxLinear MxL862xx switches" + help + Say Y or M if you want to enable support for tagging frames for the + MaxLinear MxL86252 and MxL86282 switches using their native 8-byte + tagging protocol. + +config NET_DSA_TAG_MXL_GSW1XX + tristate "Tag driver for MaxLinear GSW1xx switches" + help + The GSW1xx family of switches supports an 8-byte special tag which + can be used on the CPU port of the switch. + Say Y or M if you want to enable support for tagging frames for + MaxLinear GSW1xx switches. + +config NET_DSA_TAG_KSZ + tristate "Tag driver for Microchip 8795/937x/9477/9893 families of switches" + help + Say Y if you want to enable support for tagging frames for the + Microchip 8795/937x/9477/9893 families of switches. + +config NET_DSA_TAG_NETC + tristate "Tag driver for NXP NETC switches" + help + Say Y or M if you want to enable support for the NXP Switch Tag (NST), + as implemented by NXP NETC switches having version 4.3 or later. The + switch tag is a proprietary header added to frames after the source + MAC address, it has 3 types and each type has different subtypes, so + its length depends on the type and subtype of the tag, the maximum + length is 14 bytes. + +config NET_DSA_TAG_OCELOT + tristate "Tag driver for Ocelot family of switches, using NPI port" + select PACKING + help + Say Y or M if you want to enable NPI tagging for the Ocelot switches + (VSC7511, VSC7512, VSC7513, VSC7514, VSC9953, VSC9959). In this mode, + the frames over the Ethernet CPU port are prepended with a + hardware-defined injection/extraction frame header. Flow control + (PAUSE frames) over the CPU port is not supported when operating in + this mode. + +config NET_DSA_TAG_OCELOT_8021Q + tristate "Tag driver for Ocelot family of switches, using VLAN" + help + Say Y or M if you want to enable support for tagging frames with a + custom VLAN-based header. Frames that require timestamping, such as + PTP, are not delivered over Ethernet but over register-based MMIO. + Flow control over the CPU port is functional in this mode. When using + this mode, less TCAM resources (VCAP IS1, IS2, ES0) are available for + use with tc-flower. + +config NET_DSA_TAG_QCA + tristate "Tag driver for Qualcomm Atheros QCA8K switches" + help + Say Y or M if you want to enable support for tagging frames for + the Qualcomm Atheros QCA8K switches. + +config NET_DSA_TAG_RTL4_A + tristate "Tag driver for Realtek 4 byte protocol A tags" + help + Say Y or M if you want to enable support for tagging frames for the + Realtek switches with 4 byte protocol A tags, such as found in + the Realtek RTL8366RB. + +config NET_DSA_TAG_RTL8_4 + tristate "Tag driver for Realtek 8 byte protocol 4 tags" + help + Say Y or M if you want to enable support for tagging frames for Realtek + switches with 8 byte protocol 4 tags, such as the Realtek RTL8365MB-VC. + +config NET_DSA_TAG_RZN1_A5PSW + tristate "Tag driver for Renesas RZ/N1 A5PSW switch" + help + Say Y or M if you want to enable support for tagging frames for + Renesas RZ/N1 embedded switch that uses an 8 byte tag located after + destination MAC address. + +config NET_DSA_TAG_LAN9303 + tristate "Tag driver for SMSC/Microchip LAN9303 family of switches" + help + Say Y or M if you want to enable support for tagging frames for the + SMSC/Microchip LAN9303 family of switches. + +config NET_DSA_TAG_SJA1105 + tristate "Tag driver for NXP SJA1105 switches" + select PACKING + help + Say Y or M if you want to enable support for tagging frames with the + NXP SJA1105 switch family. Both the native tagging protocol (which + is only for link-local traffic) as well as non-native tagging (based + on a custom 802.1Q VLAN header) are available. + +config NET_DSA_TAG_TRAILER + tristate "Tag driver for switches using a trailer tag" + help + Say Y or M if you want to enable support for tagging frames at + with a trailed. e.g. Marvell 88E6060. + +config NET_DSA_TAG_VSC73XX_8021Q + tristate "Tag driver for Microchip/Vitesse VSC73xx family of switches, using VLAN" + help + Say Y or M if you want to enable support for tagging frames with a + custom VLAN-based header. + +config NET_DSA_TAG_XRS700X + tristate "Tag driver for XRS700x switches" + help + Say Y or M if you want to enable support for tagging frames for + Arrow SpeedChips XRS700x switches that use a single byte tag trailer. + +config NET_DSA_TAG_YT921X + tristate "Tag driver for Motorcomm YT921x switches" + help + Say Y or M if you want to enable support for tagging frames for + Motorcomm YT921x switches. + +endif -- cgit v1.3.1