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Date: Mon, 9 Aug 2021 15:59:09 -0500 From: Clark Williams <williams@...hat.com> To: Sebastian Andrzej Siewior <bigeasy@...utronix.de> Cc: Thomas Gleixner <tglx@...utronix.de>, Steven Rostedt <rostedt@...dmis.org>, Dmitry Vyukov <dvyukov@...gle.com>, Andrey Konovalov <andreyknvl@...il.com>, kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org Subject: [PATCH PREEMPT_RT] kcov: fix locking splat from kcov_remote_start() Saw the following splat on 5.14-rc4-rt5 with: CONFIG_KCOV=y CONFIG_KCOV_INSTRUMENT_ALL=y CONFIG_KCOV_IRQ_AREA_SIZE=0x40000 CONFIG_RUNTIME_TESTING_MENU=y kernel: ehci-pci 0000:00:1d.0: USB 2.0 started, EHCI 1.00 kernel: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:35 kernel: in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 34, name: ksoftirqd/3 kernel: 4 locks held by ksoftirqd/3/34: kernel: #0: ffff944376d989f8 ((softirq_ctrl.lock).lock){+.+.}-{2:2}, at: __local_bh_disable_ip+0xe0/0x190 kernel: #1: ffffffffbbfb61e0 (rcu_read_lock){....}-{1:2}, at: rt_spin_lock+0x5/0xd0 kernel: #2: ffffffffbbfb61e0 (rcu_read_lock){....}-{1:2}, at: __local_bh_disable_ip+0xbd/0x190 kernel: #3: ffffffffbc086518 (kcov_remote_lock){....}-{2:2}, at: kcov_remote_start+0x119/0x4a0 kernel: irq event stamp: 4653 kernel: hardirqs last enabled at (4652): [<ffffffffbafb85ce>] _raw_spin_unlock_irqrestore+0x6e/0x80 kernel: hardirqs last disabled at (4653): [<ffffffffba2517c8>] kcov_remote_start+0x298/0x4a0 kernel: softirqs last enabled at (4638): [<ffffffffba110a5b>] run_ksoftirqd+0x9b/0x100 kernel: softirqs last disabled at (4644): [<ffffffffba149f12>] smpboot_thread_fn+0x2b2/0x410 kernel: CPU: 3 PID: 34 Comm: ksoftirqd/3 Not tainted 5.14.0-rc4-rt5+ #3 kernel: Hardware name: /NUC5i7RYB, BIOS RYBDWi35.86A.0359.2016.0906.1028 09/06/2016 kernel: Call Trace: kernel: dump_stack_lvl+0x7a/0x9b kernel: ___might_sleep.cold+0xf3/0x107 kernel: rt_spin_lock+0x3a/0xd0 kernel: ? kcov_remote_start+0x119/0x4a0 kernel: kcov_remote_start+0x119/0x4a0 kernel: ? led_trigger_blink_oneshot+0x83/0xa0 kernel: __usb_hcd_giveback_urb+0x161/0x1e0 kernel: usb_giveback_urb_bh+0xb6/0x110 kernel: tasklet_action_common.constprop.0+0xe8/0x110 kernel: __do_softirq+0xe2/0x525 kernel: ? smpboot_thread_fn+0x31/0x410 kernel: run_ksoftirqd+0x8c/0x100 kernel: smpboot_thread_fn+0x2b2/0x410 kernel: ? smpboot_register_percpu_thread+0x130/0x130 kernel: kthread+0x1de/0x210 kernel: ? set_kthread_struct+0x60/0x60 kernel: ret_from_fork+0x22/0x30 kernel: usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 5.14 Change kcov_remote_lock from regular spinlock_t to raw_spinlock_t so that we don't get "sleeping function called from invalid context" on PREEMPT_RT kernel. Signed-off-by: Clark Williams <williams@...hat.com> --- kernel/kcov.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/kernel/kcov.c b/kernel/kcov.c index 80bfe71bbe13..60f903f8a46c 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -82,7 +82,7 @@ struct kcov_remote { struct hlist_node hnode; }; -static DEFINE_SPINLOCK(kcov_remote_lock); +static DEFINE_RAW_SPINLOCK(kcov_remote_lock); static DEFINE_HASHTABLE(kcov_remote_map, 4); static struct list_head kcov_remote_areas = LIST_HEAD_INIT(kcov_remote_areas); @@ -375,7 +375,7 @@ static void kcov_remote_reset(struct kcov *kcov) struct hlist_node *tmp; unsigned long flags; - spin_lock_irqsave(&kcov_remote_lock, flags); + raw_spin_lock_irqsave(&kcov_remote_lock, flags); hash_for_each_safe(kcov_remote_map, bkt, tmp, remote, hnode) { if (remote->kcov != kcov) continue; @@ -384,7 +384,7 @@ static void kcov_remote_reset(struct kcov *kcov) } /* Do reset before unlock to prevent races with kcov_remote_start(). */ kcov_reset(kcov); - spin_unlock_irqrestore(&kcov_remote_lock, flags); + raw_spin_unlock_irqrestore(&kcov_remote_lock, flags); } static void kcov_disable(struct task_struct *t, struct kcov *kcov) @@ -638,18 +638,18 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, kcov->t = t; kcov->remote = true; kcov->remote_size = remote_arg->area_size; - spin_lock_irqsave(&kcov_remote_lock, flags); + raw_spin_lock_irqsave(&kcov_remote_lock, flags); for (i = 0; i < remote_arg->num_handles; i++) { if (!kcov_check_handle(remote_arg->handles[i], false, true, false)) { - spin_unlock_irqrestore(&kcov_remote_lock, + raw_spin_unlock_irqrestore(&kcov_remote_lock, flags); kcov_disable(t, kcov); return -EINVAL; } remote = kcov_remote_add(kcov, remote_arg->handles[i]); if (IS_ERR(remote)) { - spin_unlock_irqrestore(&kcov_remote_lock, + raw_spin_unlock_irqrestore(&kcov_remote_lock, flags); kcov_disable(t, kcov); return PTR_ERR(remote); @@ -658,7 +658,7 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, if (remote_arg->common_handle) { if (!kcov_check_handle(remote_arg->common_handle, true, false, false)) { - spin_unlock_irqrestore(&kcov_remote_lock, + raw_spin_unlock_irqrestore(&kcov_remote_lock, flags); kcov_disable(t, kcov); return -EINVAL; @@ -666,14 +666,14 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, remote = kcov_remote_add(kcov, remote_arg->common_handle); if (IS_ERR(remote)) { - spin_unlock_irqrestore(&kcov_remote_lock, + raw_spin_unlock_irqrestore(&kcov_remote_lock, flags); kcov_disable(t, kcov); return PTR_ERR(remote); } t->kcov_handle = remote_arg->common_handle; } - spin_unlock_irqrestore(&kcov_remote_lock, flags); + raw_spin_unlock_irqrestore(&kcov_remote_lock, flags); /* Put either in kcov_task_exit() or in KCOV_DISABLE. */ kcov_get(kcov); return 0; @@ -845,10 +845,10 @@ void kcov_remote_start(u64 handle) return; } - spin_lock(&kcov_remote_lock); + raw_spin_lock(&kcov_remote_lock); remote = kcov_remote_find(handle); if (!remote) { - spin_unlock_irqrestore(&kcov_remote_lock, flags); + raw_spin_unlock_irqrestore(&kcov_remote_lock, flags); return; } kcov_debug("handle = %llx, context: %s\n", handle, @@ -869,7 +869,7 @@ void kcov_remote_start(u64 handle) size = CONFIG_KCOV_IRQ_AREA_SIZE; area = this_cpu_ptr(&kcov_percpu_data)->irq_area; } - spin_unlock_irqrestore(&kcov_remote_lock, flags); + raw_spin_unlock_irqrestore(&kcov_remote_lock, flags); /* Can only happen when in_task(). */ if (!area) { @@ -1008,9 +1008,9 @@ void kcov_remote_stop(void) spin_unlock(&kcov->lock); if (in_task()) { - spin_lock(&kcov_remote_lock); + raw_spin_lock(&kcov_remote_lock); kcov_remote_area_put(area, size); - spin_unlock(&kcov_remote_lock); + raw_spin_unlock(&kcov_remote_lock); } local_irq_restore(flags); -- 2.31.1 -- The United States Coast Guard Ruining Natural Selection since 1790
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