From 08b74a000942a380fe028845f92cd3a0dee827d5 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Mon, 6 May 2024 03:02:38 +0200 Subject: Adding debian version 4.19.249-2. Signed-off-by: Daniel Baumann --- ...033-net-sched-Use-msleep-instead-of-yield.patch | 64 ++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 debian/patches-rt/0033-net-sched-Use-msleep-instead-of-yield.patch (limited to 'debian/patches-rt/0033-net-sched-Use-msleep-instead-of-yield.patch') diff --git a/debian/patches-rt/0033-net-sched-Use-msleep-instead-of-yield.patch b/debian/patches-rt/0033-net-sched-Use-msleep-instead-of-yield.patch new file mode 100644 index 000000000..04ac2a1dd --- /dev/null +++ b/debian/patches-rt/0033-net-sched-Use-msleep-instead-of-yield.patch @@ -0,0 +1,64 @@ +From 6312157ef6ed82e76dfab7c719dc7b5f731eb189 Mon Sep 17 00:00:00 2001 +From: Marc Kleine-Budde +Date: Wed, 5 Mar 2014 00:49:47 +0100 +Subject: [PATCH 033/347] net: sched: Use msleep() instead of yield() +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz + +On PREEMPT_RT enabled systems the interrupt handler run as threads at prio 50 +(by default). If a high priority userspace process tries to shut down a busy +network interface it might spin in a yield loop waiting for the device to +become idle. With the interrupt thread having a lower priority than the +looping process it might never be scheduled and so result in a deadlock on UP +systems. + +With Magic SysRq the following backtrace can be produced: + +> test_app R running 0 174 168 0x00000000 +> [] (__schedule+0x220/0x3fc) from [] (preempt_schedule_irq+0x48/0x80) +> [] (preempt_schedule_irq+0x48/0x80) from [] (svc_preempt+0x8/0x20) +> [] (svc_preempt+0x8/0x20) from [] (local_bh_enable+0x18/0x88) +> [] (local_bh_enable+0x18/0x88) from [] (dev_deactivate_many+0x220/0x264) +> [] (dev_deactivate_many+0x220/0x264) from [] (__dev_close_many+0x64/0xd4) +> [] (__dev_close_many+0x64/0xd4) from [] (__dev_close+0x28/0x3c) +> [] (__dev_close+0x28/0x3c) from [] (__dev_change_flags+0x88/0x130) +> [] (__dev_change_flags+0x88/0x130) from [] (dev_change_flags+0x10/0x48) +> [] (dev_change_flags+0x10/0x48) from [] (do_setlink+0x370/0x7ec) +> [] (do_setlink+0x370/0x7ec) from [] (rtnl_newlink+0x2b4/0x450) +> [] (rtnl_newlink+0x2b4/0x450) from [] (rtnetlink_rcv_msg+0x158/0x1f4) +> [] (rtnetlink_rcv_msg+0x158/0x1f4) from [] (netlink_rcv_skb+0xac/0xc0) +> [] (netlink_rcv_skb+0xac/0xc0) from [] (rtnetlink_rcv+0x18/0x24) +> [] (rtnetlink_rcv+0x18/0x24) from [] (netlink_unicast+0x13c/0x198) +> [] (netlink_unicast+0x13c/0x198) from [] (netlink_sendmsg+0x264/0x2e0) +> [] (netlink_sendmsg+0x264/0x2e0) from [] (sock_sendmsg+0x78/0x98) +> [] (sock_sendmsg+0x78/0x98) from [] (___sys_sendmsg.part.25+0x268/0x278) +> [] (___sys_sendmsg.part.25+0x268/0x278) from [] (__sys_sendmsg+0x48/0x78) +> [] (__sys_sendmsg+0x48/0x78) from [] (ret_fast_syscall+0x0/0x2c) + +This patch works around the problem by replacing yield() by msleep(1), giving +the interrupt thread time to finish, similar to other changes contained in the +rt patch set. Using wait_for_completion() instead would probably be a better +solution. + + +Signed-off-by: Marc Kleine-Budde +Signed-off-by: Sebastian Andrzej Siewior +--- + net/sched/sch_generic.c | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c +index 7c1b1eff84f4..42a776abdf2f 100644 +--- a/net/sched/sch_generic.c ++++ b/net/sched/sch_generic.c +@@ -1253,7 +1253,7 @@ void dev_deactivate_many(struct list_head *head) + /* Wait for outstanding qdisc_run calls. */ + list_for_each_entry(dev, head, close_list) { + while (some_qdisc_is_busy(dev)) +- yield(); ++ msleep(1); + /* The new qdisc is assigned at this point so we can safely + * unwind stale skb lists and qdisc statistics + */ +-- +2.36.1 + -- cgit v1.2.3