From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- net/lapb/lapb_timer.c | 206 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 206 insertions(+) create mode 100644 net/lapb/lapb_timer.c (limited to 'net/lapb/lapb_timer.c') diff --git a/net/lapb/lapb_timer.c b/net/lapb/lapb_timer.c new file mode 100644 index 000000000..9fde6cf20 --- /dev/null +++ b/net/lapb/lapb_timer.c @@ -0,0 +1,206 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * LAPB release 002 + * + * This code REQUIRES 2.1.15 or higher/ NET3.038 + * + * History + * LAPB 001 Jonathan Naylor Started Coding + * LAPB 002 Jonathan Naylor New timer architecture. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static void lapb_t1timer_expiry(struct timer_list *); +static void lapb_t2timer_expiry(struct timer_list *); + +void lapb_start_t1timer(struct lapb_cb *lapb) +{ + timer_delete(&lapb->t1timer); + + lapb->t1timer.function = lapb_t1timer_expiry; + lapb->t1timer.expires = jiffies + lapb->t1; + + lapb->t1timer_running = true; + add_timer(&lapb->t1timer); +} + +void lapb_start_t2timer(struct lapb_cb *lapb) +{ + timer_delete(&lapb->t2timer); + + lapb->t2timer.function = lapb_t2timer_expiry; + lapb->t2timer.expires = jiffies + lapb->t2; + + lapb->t2timer_running = true; + add_timer(&lapb->t2timer); +} + +void lapb_stop_t1timer(struct lapb_cb *lapb) +{ + lapb->t1timer_running = false; + timer_delete(&lapb->t1timer); +} + +void lapb_stop_t2timer(struct lapb_cb *lapb) +{ + lapb->t2timer_running = false; + timer_delete(&lapb->t2timer); +} + +int lapb_t1timer_running(struct lapb_cb *lapb) +{ + return lapb->t1timer_running; +} + +static void lapb_t2timer_expiry(struct timer_list *t) +{ + struct lapb_cb *lapb = timer_container_of(lapb, t, t2timer); + + spin_lock_bh(&lapb->lock); + if (timer_pending(&lapb->t2timer)) /* A new timer has been set up */ + goto out; + if (!lapb->t2timer_running) /* The timer has been stopped */ + goto out; + + if (lapb->condition & LAPB_ACK_PENDING_CONDITION) { + lapb->condition &= ~LAPB_ACK_PENDING_CONDITION; + lapb_timeout_response(lapb); + } + lapb->t2timer_running = false; + +out: + spin_unlock_bh(&lapb->lock); +} + +static void lapb_t1timer_expiry(struct timer_list *t) +{ + struct lapb_cb *lapb = timer_container_of(lapb, t, t1timer); + + spin_lock_bh(&lapb->lock); + if (timer_pending(&lapb->t1timer)) /* A new timer has been set up */ + goto out; + if (!lapb->t1timer_running) /* The timer has been stopped */ + goto out; + + switch (lapb->state) { + + /* + * If we are a DCE, send DM up to N2 times, then switch to + * STATE_1 and send SABM(E). + */ + case LAPB_STATE_0: + if (lapb->mode & LAPB_DCE && + lapb->n2count != lapb->n2) { + lapb->n2count++; + lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE); + } else { + lapb->state = LAPB_STATE_1; + lapb_establish_data_link(lapb); + } + break; + + /* + * Awaiting connection state, send SABM(E), up to N2 times. + */ + case LAPB_STATE_1: + if (lapb->n2count == lapb->n2) { + lapb_clear_queues(lapb); + lapb->state = LAPB_STATE_0; + lapb_disconnect_indication(lapb, LAPB_TIMEDOUT); + lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev); + lapb->t1timer_running = false; + goto out; + } else { + lapb->n2count++; + if (lapb->mode & LAPB_EXTENDED) { + lapb_dbg(1, "(%p) S1 TX SABME(1)\n", + lapb->dev); + lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND); + } else { + lapb_dbg(1, "(%p) S1 TX SABM(1)\n", + lapb->dev); + lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND); + } + } + break; + + /* + * Awaiting disconnection state, send DISC, up to N2 times. + */ + case LAPB_STATE_2: + if (lapb->n2count == lapb->n2) { + lapb_clear_queues(lapb); + lapb->state = LAPB_STATE_0; + lapb_disconnect_confirmation(lapb, LAPB_TIMEDOUT); + lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev); + lapb->t1timer_running = false; + goto out; + } else { + lapb->n2count++; + lapb_dbg(1, "(%p) S2 TX DISC(1)\n", lapb->dev); + lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND); + } + break; + + /* + * Data transfer state, restransmit I frames, up to N2 times. + */ + case LAPB_STATE_3: + if (lapb->n2count == lapb->n2) { + lapb_clear_queues(lapb); + lapb->state = LAPB_STATE_0; + lapb_stop_t2timer(lapb); + lapb_disconnect_indication(lapb, LAPB_TIMEDOUT); + lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev); + lapb->t1timer_running = false; + goto out; + } else { + lapb->n2count++; + lapb_requeue_frames(lapb); + lapb_kick(lapb); + } + break; + + /* + * Frame reject state, restransmit FRMR frames, up to N2 times. + */ + case LAPB_STATE_4: + if (lapb->n2count == lapb->n2) { + lapb_clear_queues(lapb); + lapb->state = LAPB_STATE_0; + lapb_disconnect_indication(lapb, LAPB_TIMEDOUT); + lapb_dbg(0, "(%p) S4 -> S0\n", lapb->dev); + lapb->t1timer_running = false; + goto out; + } else { + lapb->n2count++; + lapb_transmit_frmr(lapb); + } + break; + } + + lapb_start_t1timer(lapb); + +out: + spin_unlock_bh(&lapb->lock); +} -- cgit v1.3.1