[syzbot] [wireless?] [net?] WARNING in ieee80211_rfkill_poll

[syzbot] [wireless?] [net?] WARNING in ieee80211_rfkill_poll

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    90b0c2b2edd1 Merge tag 'pinctrl-v6.7-1' of git://git.kerne..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
console output: https://syzkaller.appspot.com/x/log.txt?x=1437f47b680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b0220f5f3436eb1a
dashboard link: https://syzkaller.appspot.com/bug?extid=7e59a5bfc7a897247e18
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13c670c0e80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1310d47b680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/38f32e2d2d96/disk-90b0c2b2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ec454d0d1d26/vmlinux-90b0c2b2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/110137c447a9/bzImage-90b0c2b2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7e59a5bfc7a897247e18@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 732 at net/mac80211/driver-ops.h:688 drv_rfkill_poll net/mac80211/driver-ops.h:688 [inline]
WARNING: CPU: 1 PID: 732 at net/mac80211/driver-ops.h:688 ieee80211_rfkill_poll+0x134/0x170 net/mac80211/cfg.c:3100
Modules linked in:
CPU: 1 PID: 732 Comm: kworker/1:2 Not tainted 6.6.0-syzkaller-14142-g90b0c2b2edd1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
Workqueue: events_power_efficient rfkill_poll
RIP: 0010:drv_rfkill_poll net/mac80211/driver-ops.h:688 [inline]
RIP: 0010:ieee80211_rfkill_poll+0x134/0x170 net/mac80211/cfg.c:3100
Code: 60 07 00 00 be ff ff ff ff 48 8d 78 68 e8 44 f4 38 00 31 ff 89 c5 89 c6 e8 89 59 39 fb 85 ed 0f 85 44 ff ff ff e8 0c 5e 39 fb <0f> 0b e9 38 ff ff ff e8 00 5e 39 fb 0f 0b 48 c7 c7 f8 16 34 89 e8
RSP: 0018:ffffc90001cafc90 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888100ff0700 RCX: ffffffff8614b267
RDX: ffff888107368000 RSI: ffffffff8614b274 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 1ffffffff15c0565 R12: ffff888100ff0700
R13: 0000000000000001 R14: ffffc90001cafd80 R15: ffff8881f673ad40
FS:  0000000000000000(0000) GS:ffff8881f6700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6477ad0e40 CR3: 00000001122fe000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 rdev_rfkill_poll net/wireless/rdev-ops.h:636 [inline]
 cfg80211_rfkill_poll+0xc9/0x240 net/wireless/core.c:224
 rfkill_poll+0x8d/0x110 net/rfkill/core.c:1037
 process_one_work+0x884/0x15c0 kernel/workqueue.c:2630
 process_scheduled_works kernel/workqueue.c:2703 [inline]
 worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784
 kthread+0x33c/0x440 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
 </TASK>


---
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Re: [syzbot] Test

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Subject: Test
Author: mukattreyee@gmail.com

#syz test:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

Re: [syzbot] test

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Subject: test
Author: danielyangkang@gmail.com

#syz test

Re: [syzbot] test

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Subject: test
Author: danielyangkang@gmail.com

#syz test

Re: [syzbot] Test

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Subject: Test
Author: radoslaw.zielonek@gmail.com

#syz test 

---
 include/linux/sched.h |  7 +++++++
 kernel/sched/core.c   |  1 +
 kernel/sched/rt.c     | 26 +++++++++++++++++++++++---
 kernel/signal.c       |  9 +++++++++
 4 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 17cb0761ff65..123bc16ad3d0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1121,6 +1121,13 @@ struct task_struct {
 	size_t				sas_ss_size;
 	unsigned int			sas_ss_flags;
 
+	/*
+	 * Number of signals received by an RT task between scheduling ticks.
+	 * This counter is used to throttle RT tasks when too many signals
+	 * (e.g., POSIX timers) are sent to the task, which can cause an RCU stall.
+	 */
+	atomic_t rt_signals_recv_count; /* used outside of the rq lock */
+
 	struct callback_head		*task_works;
 
 #ifdef CONFIG_AUDIT
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d44efa0d0611..9def826bd35f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4779,6 +4779,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
 			p->policy = SCHED_NORMAL;
 			p->static_prio = NICE_TO_PRIO(0);
 			p->rt_priority = 0;
+			atomic_set(&p->rt_signals_recv_count, 0);
 		} else if (PRIO_TO_NICE(p->static_prio) < 0)
 			p->static_prio = NICE_TO_PRIO(0);
 
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 3261b067b67e..9b22d67d1746 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -24,6 +24,15 @@ int sysctl_sched_rt_period = 1000000;
  */
 int sysctl_sched_rt_runtime = 950000;
 
+/*
+ * To avoid an RCU stall due to a large number of signals received by RT tasks
+ * (e.g., POSIX timers), the RT task needs to be throttled.
+ * When the number of signals received by an RT task during a scheduling
+ * tick period exceeds the threshold, the RT task will be throttled.
+ * The value of 100 has not been thoroughly tested and may need adjustment.
+ */
+#define RT_RECV_SGINAL_THROTTLE_THRESHOLD 100
+
 #ifdef CONFIG_SYSCTL
 static int sysctl_sched_rr_timeslice = (MSEC_PER_SEC * RR_TIMESLICE) / HZ;
 static int sched_rt_handler(struct ctl_table *table, int write, void *buffer,
@@ -951,7 +960,7 @@ static inline int rt_se_prio(struct sched_rt_entity *rt_se)
 	return rt_task_of(rt_se)->prio;
 }
 
-static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
+static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq, int rt_signal_recv)
 {
 	u64 runtime = sched_rt_runtime(rt_rq);
 
@@ -966,7 +975,15 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
 	if (runtime == RUNTIME_INF)
 		return 0;
 
-	if (rt_rq->rt_time > runtime) {
+	/*
+	 * When a large number of signals are sent to this task (e.g., POSIX timers)
+	 * the delta time deviates significantly from real time due to the overhead
+	 * of handling signals. For RT tasks, this can cause an RCU stall.
+	 * To avoid this, throttle the task when the number of signals received
+	 * exceeds a certain threshold.
+	 */
+	if (rt_rq->rt_time > runtime ||
+		rt_signal_recv >= RT_RECV_SGINAL_THROTTLE_THRESHOLD) {
 		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
 
 		/*
@@ -1021,7 +1038,9 @@ static void update_curr_rt(struct rq *rq)
 		if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
 			raw_spin_lock(&rt_rq->rt_runtime_lock);
 			rt_rq->rt_time += delta_exec;
-			exceeded = sched_rt_runtime_exceeded(rt_rq);
+			exceeded = sched_rt_runtime_exceeded(
+						rt_rq,
+						atomic_read(&curr->rt_signals_recv_count));
 			if (exceeded)
 				resched_curr(rq);
 			raw_spin_unlock(&rt_rq->rt_runtime_lock);
@@ -1029,6 +1048,7 @@ static void update_curr_rt(struct rq *rq)
 				do_start_rt_bandwidth(sched_rt_bandwidth(rt_rq));
 		}
 	}
+	atomic_set(&curr->rt_signals_recv_count, 0);
 }
 
 static void
diff --git a/kernel/signal.c b/kernel/signal.c
index bdca529f0f7b..d58e0ba9336c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -629,6 +629,15 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask,
 	bool resched_timer = false;
 	int signr;
 
+	/*
+	 * To prevent an RCU stall due to receiving too many signals by RT tasks,
+	 * count all signals regardless of their type.
+	 * Based on this counter, the RT scheduler will decide whether the task
+	 * should be throttled or not.
+	 */
+	if (tsk->policy == SCHED_FIFO || tsk->policy == SCHED_RR)
+		atomic_inc(&tsk->rt_signals_recv_count);
+
 	/* We only dequeue private signals from ourselves, we don't let
 	 * signalfd steal them
 	 */
-- 
2.43.0

Re: [syzbot] Test

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: Test
Author: radoslaw.zielonek@gmail.com

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git dccb07f2914cdab2ac3a5b6c98406f765acab803

---
 include/linux/sched.h |  7 +++++++
 kernel/sched/core.c   |  1 +
 kernel/sched/rt.c     | 26 +++++++++++++++++++++++---
 kernel/signal.c       |  9 +++++++++
 4 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 17cb0761ff65..123bc16ad3d0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1121,6 +1121,13 @@ struct task_struct {
 	size_t				sas_ss_size;
 	unsigned int			sas_ss_flags;
 
+	/*
+	 * Number of signals received by an RT task between scheduling ticks.
+	 * This counter is used to throttle RT tasks when too many signals
+	 * (e.g., POSIX timers) are sent to the task, which can cause an RCU stall.
+	 */
+	atomic_t rt_signals_recv_count; /* used outside of the rq lock */
+
 	struct callback_head		*task_works;
 
 #ifdef CONFIG_AUDIT
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d44efa0d0611..9def826bd35f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4779,6 +4779,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
 			p->policy = SCHED_NORMAL;
 			p->static_prio = NICE_TO_PRIO(0);
 			p->rt_priority = 0;
+			atomic_set(&p->rt_signals_recv_count, 0);
 		} else if (PRIO_TO_NICE(p->static_prio) < 0)
 			p->static_prio = NICE_TO_PRIO(0);
 
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 3261b067b67e..9b22d67d1746 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -24,6 +24,15 @@ int sysctl_sched_rt_period = 1000000;
  */
 int sysctl_sched_rt_runtime = 950000;
 
+/*
+ * To avoid an RCU stall due to a large number of signals received by RT tasks
+ * (e.g., POSIX timers), the RT task needs to be throttled.
+ * When the number of signals received by an RT task during a scheduling
+ * tick period exceeds the threshold, the RT task will be throttled.
+ * The value of 100 has not been thoroughly tested and may need adjustment.
+ */
+#define RT_RECV_SGINAL_THROTTLE_THRESHOLD 100
+
 #ifdef CONFIG_SYSCTL
 static int sysctl_sched_rr_timeslice = (MSEC_PER_SEC * RR_TIMESLICE) / HZ;
 static int sched_rt_handler(struct ctl_table *table, int write, void *buffer,
@@ -951,7 +960,7 @@ static inline int rt_se_prio(struct sched_rt_entity *rt_se)
 	return rt_task_of(rt_se)->prio;
 }
 
-static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
+static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq, int rt_signal_recv)
 {
 	u64 runtime = sched_rt_runtime(rt_rq);
 
@@ -966,7 +975,15 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
 	if (runtime == RUNTIME_INF)
 		return 0;
 
-	if (rt_rq->rt_time > runtime) {
+	/*
+	 * When a large number of signals are sent to this task (e.g., POSIX timers)
+	 * the delta time deviates significantly from real time due to the overhead
+	 * of handling signals. For RT tasks, this can cause an RCU stall.
+	 * To avoid this, throttle the task when the number of signals received
+	 * exceeds a certain threshold.
+	 */
+	if (rt_rq->rt_time > runtime ||
+		rt_signal_recv >= RT_RECV_SGINAL_THROTTLE_THRESHOLD) {
 		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
 
 		/*
@@ -1021,7 +1038,9 @@ static void update_curr_rt(struct rq *rq)
 		if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
 			raw_spin_lock(&rt_rq->rt_runtime_lock);
 			rt_rq->rt_time += delta_exec;
-			exceeded = sched_rt_runtime_exceeded(rt_rq);
+			exceeded = sched_rt_runtime_exceeded(
+						rt_rq,
+						atomic_read(&curr->rt_signals_recv_count));
 			if (exceeded)
 				resched_curr(rq);
 			raw_spin_unlock(&rt_rq->rt_runtime_lock);
@@ -1029,6 +1048,7 @@ static void update_curr_rt(struct rq *rq)
 				do_start_rt_bandwidth(sched_rt_bandwidth(rt_rq));
 		}
 	}
+	atomic_set(&curr->rt_signals_recv_count, 0);
 }
 
 static void
diff --git a/kernel/signal.c b/kernel/signal.c
index bdca529f0f7b..d58e0ba9336c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -629,6 +629,15 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask,
 	bool resched_timer = false;
 	int signr;
 
+	/*
+	 * To prevent an RCU stall due to receiving too many signals by RT tasks,
+	 * count all signals regardless of their type.
+	 * Based on this counter, the RT scheduler will decide whether the task
+	 * should be throttled or not.
+	 */
+	if (tsk->policy == SCHED_FIFO || tsk->policy == SCHED_RR)
+		atomic_inc(&tsk->rt_signals_recv_count);
+
 	/* We only dequeue private signals from ourselves, we don't let
 	 * signalfd steal them
 	 */
-- 
2.43.0

Re: [syzbot] Test

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: Test
Author: radoslaw.zielonek@gmail.com

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git fe46a7dd189e25604716c03576d05ac8a5209743

---
 include/linux/sched.h |  7 +++++++
 kernel/sched/core.c   |  1 +
 kernel/sched/rt.c     | 26 +++++++++++++++++++++++---
 kernel/signal.c       |  9 +++++++++
 4 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 17cb0761ff65..123bc16ad3d0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1121,6 +1121,13 @@ struct task_struct {
 	size_t				sas_ss_size;
 	unsigned int			sas_ss_flags;
 
+	/*
+	 * Number of signals received by an RT task between scheduling ticks.
+	 * This counter is used to throttle RT tasks when too many signals
+	 * (e.g., POSIX timers) are sent to the task, which can cause an RCU stall.
+	 */
+	atomic_t rt_signals_recv_count; /* used outside of the rq lock */
+
 	struct callback_head		*task_works;
 
 #ifdef CONFIG_AUDIT
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d44efa0d0611..9def826bd35f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4779,6 +4779,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
 			p->policy = SCHED_NORMAL;
 			p->static_prio = NICE_TO_PRIO(0);
 			p->rt_priority = 0;
+			atomic_set(&p->rt_signals_recv_count, 0);
 		} else if (PRIO_TO_NICE(p->static_prio) < 0)
 			p->static_prio = NICE_TO_PRIO(0);
 
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 3261b067b67e..9b22d67d1746 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -24,6 +24,15 @@ int sysctl_sched_rt_period = 1000000;
  */
 int sysctl_sched_rt_runtime = 950000;
 
+/*
+ * To avoid an RCU stall due to a large number of signals received by RT tasks
+ * (e.g., POSIX timers), the RT task needs to be throttled.
+ * When the number of signals received by an RT task during a scheduling
+ * tick period exceeds the threshold, the RT task will be throttled.
+ * The value of 100 has not been thoroughly tested and may need adjustment.
+ */
+#define RT_RECV_SGINAL_THROTTLE_THRESHOLD 100
+
 #ifdef CONFIG_SYSCTL
 static int sysctl_sched_rr_timeslice = (MSEC_PER_SEC * RR_TIMESLICE) / HZ;
 static int sched_rt_handler(struct ctl_table *table, int write, void *buffer,
@@ -951,7 +960,7 @@ static inline int rt_se_prio(struct sched_rt_entity *rt_se)
 	return rt_task_of(rt_se)->prio;
 }
 
-static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
+static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq, int rt_signal_recv)
 {
 	u64 runtime = sched_rt_runtime(rt_rq);
 
@@ -966,7 +975,15 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
 	if (runtime == RUNTIME_INF)
 		return 0;
 
-	if (rt_rq->rt_time > runtime) {
+	/*
+	 * When a large number of signals are sent to this task (e.g., POSIX timers)
+	 * the delta time deviates significantly from real time due to the overhead
+	 * of handling signals. For RT tasks, this can cause an RCU stall.
+	 * To avoid this, throttle the task when the number of signals received
+	 * exceeds a certain threshold.
+	 */
+	if (rt_rq->rt_time > runtime ||
+		rt_signal_recv >= RT_RECV_SGINAL_THROTTLE_THRESHOLD) {
 		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
 
 		/*
@@ -1021,7 +1038,9 @@ static void update_curr_rt(struct rq *rq)
 		if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
 			raw_spin_lock(&rt_rq->rt_runtime_lock);
 			rt_rq->rt_time += delta_exec;
-			exceeded = sched_rt_runtime_exceeded(rt_rq);
+			exceeded = sched_rt_runtime_exceeded(
+						rt_rq,
+						atomic_read(&curr->rt_signals_recv_count));
 			if (exceeded)
 				resched_curr(rq);
 			raw_spin_unlock(&rt_rq->rt_runtime_lock);
@@ -1029,6 +1048,7 @@ static void update_curr_rt(struct rq *rq)
 				do_start_rt_bandwidth(sched_rt_bandwidth(rt_rq));
 		}
 	}
+	atomic_set(&curr->rt_signals_recv_count, 0);
 }
 
 static void
diff --git a/kernel/signal.c b/kernel/signal.c
index bdca529f0f7b..d58e0ba9336c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -629,6 +629,15 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask,
 	bool resched_timer = false;
 	int signr;
 
+	/*
+	 * To prevent an RCU stall due to receiving too many signals by RT tasks,
+	 * count all signals regardless of their type.
+	 * Based on this counter, the RT scheduler will decide whether the task
+	 * should be throttled or not.
+	 */
+	if (tsk->policy == SCHED_FIFO || tsk->policy == SCHED_RR)
+		atomic_inc(&tsk->rt_signals_recv_count);
+
 	/* We only dequeue private signals from ourselves, we don't let
 	 * signalfd steal them
 	 */
-- 
2.43.0

Re: [syzbot] test

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: test
Author: mukattreyee@gmail.com

#syz test:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

Re: [syzbot] Test

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

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Subject: Test
Author: radoslaw.zielonek@gmail.com

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 71b1543c83d65af8215d7558d70fc2ecbee77dcf

---
 net/sched/sch_taprio.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index a0d54b422186..41add4a1d407 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -44,6 +44,8 @@ static struct static_key_false taprio_have_working_mqprio;
 	(TCA_TAPRIO_ATTR_FLAG_TXTIME_ASSIST | TCA_TAPRIO_ATTR_FLAG_FULL_OFFLOAD)
 #define TAPRIO_FLAGS_INVALID U32_MAX
 
+#define TAPRIO_MAX_NUM_SCHEDULES_BEFORE_NOW 10
+
 struct sched_entry {
 	/* Durations between this GCL entry and the GCL entry where the
 	 * respective traffic class gate closes
@@ -62,6 +64,8 @@ struct sched_entry {
 	u32 gate_mask;
 	u32 interval;
 	u8 command;
+	/* Used to skip some cycles to prevent other tasks from starving */
+	u8 num_schedules_before_now;
 };
 
 struct sched_gate_list {
@@ -111,6 +115,9 @@ struct __tc_taprio_qopt_offload {
 	struct tc_taprio_qopt_offload offload;
 };
 
+static void setup_txtime(struct taprio_sched *q,
+			 struct sched_gate_list *sched, ktime_t base);
+
 static void taprio_calculate_gate_durations(struct taprio_sched *q,
 					    struct sched_gate_list *sched)
 {
@@ -919,6 +926,7 @@ static enum hrtimer_restart advance_sched(struct hrtimer *timer)
 	struct sched_entry *entry, *next;
 	struct Qdisc *sch = q->root;
 	ktime_t end_time;
+	ktime_t basenow;
 	int tc;
 
 	spin_lock(&q->current_entry_lock);
@@ -977,6 +985,23 @@ static enum hrtimer_restart advance_sched(struct hrtimer *timer)
 	taprio_set_budgets(q, oper, next);
 
 first_run:
+	basenow = ktime_get();
+	if (ktime_before(end_time, basenow))
+	{
+		next->num_schedules_before_now++;
+		if (next->num_schedules_before_now >= TAPRIO_MAX_NUM_SCHEDULES_BEFORE_NOW)
+		{
+			end_time = ktime_add_ns(basenow, oper->cycle_time);
+			next->end_time = end_time;
+			next->num_schedules_before_now = 0;
+			setup_txtime(q, oper, basenow);
+		}
+	}
+	else
+	{
+		next->num_schedules_before_now = 0;
+	}
+
 	rcu_assign_pointer(q->current_entry, next);
 	spin_unlock(&q->current_entry_lock);
 
@@ -1074,6 +1099,7 @@ static int parse_sched_entry(struct taprio_sched *q, struct nlattr *n,
 	}
 
 	entry->index = index;
+	entry->num_schedules_before_now = 0;
 
 	return fill_sched_entry(q, tb, entry, extack);
 }
-- 
2.43.0

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