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 --- drivers/net/arcnet/com20020.h | 132 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 132 insertions(+) create mode 100644 drivers/net/arcnet/com20020.h (limited to 'drivers/net/arcnet/com20020.h') diff --git a/drivers/net/arcnet/com20020.h b/drivers/net/arcnet/com20020.h new file mode 100644 index 000000000..68f49fdc2 --- /dev/null +++ b/drivers/net/arcnet/com20020.h @@ -0,0 +1,132 @@ +/* + * Linux ARCnet driver - COM20020 chipset support - function declarations + * + * Written 1997 by David Woodhouse. + * Written 1994-1999 by Avery Pennarun. + * Derived from skeleton.c by Donald Becker. + * + * Special thanks to Contemporary Controls, Inc. (www.ccontrols.com) + * for sponsoring the further development of this driver. + * + * ********************** + * + * The original copyright of skeleton.c was as follows: + * + * skeleton.c Written 1993 by Donald Becker. + * Copyright 1993 United States Government as represented by the + * Director, National Security Agency. This software may only be used + * and distributed according to the terms of the GNU General Public License as + * modified by SRC, incorporated herein by reference. + * + * ********************** + * + * For more details, see drivers/net/arcnet.c + * + * ********************** + */ +#ifndef __COM20020_H +#define __COM20020_H +#include + +int com20020_check(struct net_device *dev); +int com20020_found(struct net_device *dev, int shared); +extern const struct net_device_ops com20020_netdev_ops; + +/* The number of low I/O ports used by the card. */ +#define ARCNET_TOTAL_SIZE 8 + +#define PLX_PCI_MAX_CARDS 2 + +struct ledoffsets { + int green; + int red; +}; + +struct com20020_pci_channel_map { + u32 bar; + u32 offset; + u32 size; /* 0x00 - auto, e.g. length of entire bar */ +}; + +struct com20020_pci_card_info { + const char *name; + u8 devcount; + + struct com20020_pci_channel_map chan_map_tbl[PLX_PCI_MAX_CARDS]; + struct com20020_pci_channel_map misc_map; + + struct ledoffsets leds[PLX_PCI_MAX_CARDS]; + int rotary; + + unsigned int flags; +}; + +struct com20020_priv { + struct com20020_pci_card_info *ci; + struct list_head list_dev; + resource_size_t misc; +}; + +struct com20020_dev { + struct list_head list; + struct net_device *dev; + + struct led_classdev tx_led; + struct led_classdev recon_led; + + struct com20020_priv *pci_priv; + int index; +}; + +#define COM20020_REG_W_INTMASK 0 /* writable */ +#define COM20020_REG_R_STATUS 0 /* readable */ +#define COM20020_REG_W_COMMAND 1 /* standard arcnet commands */ +#define COM20020_REG_R_DIAGSTAT 1 /* diagnostic status */ +#define COM20020_REG_W_ADDR_HI 2 /* control for IO-mapped memory */ +#define COM20020_REG_W_ADDR_LO 3 +#define COM20020_REG_RW_MEMDATA 4 /* data port for IO-mapped memory */ +#define COM20020_REG_W_SUBADR 5 /* the extended port _XREG refers to */ +#define COM20020_REG_W_CONFIG 6 /* configuration */ +#define COM20020_REG_W_XREG 7 /* extra + * (indexed by _CONFIG or _SUBADDR) + */ + +/* in the ADDR_HI register */ +#define RDDATAflag 0x80 /* next access is a read (not a write) */ + +/* in the DIAGSTAT register */ +#define NEWNXTIDflag 0x02 /* ID to which token is passed has changed */ + +/* in the CONFIG register */ +#define RESETcfg 0x80 /* put card in reset state */ +#define TXENcfg 0x20 /* enable TX */ +#define XTOcfg(x) ((x) << 3) /* extended timeout */ + +/* in SETUP register */ +#define PROMISCset 0x10 /* enable RCV_ALL */ +#define P1MODE 0x80 /* enable P1-MODE for Backplane */ +#define SLOWARB 0x01 /* enable Slow Arbitration for >=5Mbps */ + +/* COM2002x */ +#define SUB_TENTATIVE 0 /* tentative node ID */ +#define SUB_NODE 1 /* node ID */ +#define SUB_SETUP1 2 /* various options */ +#define SUB_TEST 3 /* test/diag register */ + +/* COM20022 only */ +#define SUB_SETUP2 4 /* sundry options */ +#define SUB_BUSCTL 5 /* bus control options */ +#define SUB_DMACOUNT 6 /* DMA count options */ + +static inline void com20020_set_subaddress(struct arcnet_local *lp, + int ioaddr, int val) +{ + if (val < 4) { + lp->config = (lp->config & ~0x03) | val; + outb(lp->config, ioaddr + COM20020_REG_W_CONFIG); + } else { + outb(val, ioaddr + COM20020_REG_W_SUBADR); + } +} + +#endif /* __COM20020_H */ -- cgit v1.3.1