Revision be65e2595b4c1fbeceba336d8ee83406726b1d8d authored by Linus Torvalds on 06 September 2018, 16:06:49 UTC, committed by Linus Torvalds on 06 September 2018, 16:06:49 UTC
Pull tracing fixes from Steven Rostedt: "This fixes two annoying bugs: - The first one is a side effect caused by using SRCU for rcuidle tracepoints. It seems that the perf was depending on the rcuidle tracepoints to make RCU watch when it wasn't. The real fix will be to have perf use SRCU instead of depending on RCU watching, but that can't be done until SRCU is safe to use in NMI context (Paul's working on that). - The second bug fix is for a bug that's been periodically making my tests fail randomly for some time. I haven't had time to track it down, but finally have. It has to do with stressing NMIs (via perf) while enabling or disabling ftrace function handling with lockdep enabled. If an interrupt happens and just as it returns, it sets lockdep back to "interrupts enabled" but before it returns an NMI is triggered, and if this happens while printk_nmi_enter has a breakpoint attached to it (because ftrace is converting it to or from nop to call fentry), the breakpoint trap also calls into lockdep, and since returning from the NMI to a interrupt handler, interrupts were disabled when the NMI went off, lockdep keeps its state as interrupts disabled when it returns back from the interrupt handler where interrupts are enabled. This causes lockdep_assert_irqs_enabled() to trigger a false positive" * tag 'trace-v4.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: printk/tracing: Do not trace printk_nmi_enter() tracing: Add back in rcu_irq_enter/exit_irqson() for rcuidle tracepoints
x25_out.c
/*
* X.25 Packet Layer release 002
*
* This is ALPHA test software. This code may break your machine,
* randomly fail to work with new releases, misbehave and/or generally
* screw up. It might even work.
*
* This code REQUIRES 2.1.15 or higher
*
* This module:
* This module is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* History
* X.25 001 Jonathan Naylor Started coding.
* X.25 002 Jonathan Naylor New timer architecture.
* 2000-09-04 Henner Eisen Prevented x25_output() skb leakage.
* 2000-10-27 Henner Eisen MSG_DONTWAIT for fragment allocation.
* 2000-11-10 Henner Eisen x25_send_iframe(): re-queued frames
* needed cleaned seq-number fields.
*/
#include <linux/slab.h>
#include <linux/socket.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/x25.h>
static int x25_pacsize_to_bytes(unsigned int pacsize)
{
int bytes = 1;
if (!pacsize)
return 128;
while (pacsize-- > 0)
bytes *= 2;
return bytes;
}
/*
* This is where all X.25 information frames pass.
*
* Returns the amount of user data bytes sent on success
* or a negative error code on failure.
*/
int x25_output(struct sock *sk, struct sk_buff *skb)
{
struct sk_buff *skbn;
unsigned char header[X25_EXT_MIN_LEN];
int err, frontlen, len;
int sent=0, noblock = X25_SKB_CB(skb)->flags & MSG_DONTWAIT;
struct x25_sock *x25 = x25_sk(sk);
int header_len = x25->neighbour->extended ? X25_EXT_MIN_LEN :
X25_STD_MIN_LEN;
int max_len = x25_pacsize_to_bytes(x25->facilities.pacsize_out);
if (skb->len - header_len > max_len) {
/* Save a copy of the Header */
skb_copy_from_linear_data(skb, header, header_len);
skb_pull(skb, header_len);
frontlen = skb_headroom(skb);
while (skb->len > 0) {
release_sock(sk);
skbn = sock_alloc_send_skb(sk, frontlen + max_len,
noblock, &err);
lock_sock(sk);
if (!skbn) {
if (err == -EWOULDBLOCK && noblock){
kfree_skb(skb);
return sent;
}
SOCK_DEBUG(sk, "x25_output: fragment alloc"
" failed, err=%d, %d bytes "
"sent\n", err, sent);
return err;
}
skb_reserve(skbn, frontlen);
len = max_len > skb->len ? skb->len : max_len;
/* Copy the user data */
skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
skb_pull(skb, len);
/* Duplicate the Header */
skb_push(skbn, header_len);
skb_copy_to_linear_data(skbn, header, header_len);
if (skb->len > 0) {
if (x25->neighbour->extended)
skbn->data[3] |= X25_EXT_M_BIT;
else
skbn->data[2] |= X25_STD_M_BIT;
}
skb_queue_tail(&sk->sk_write_queue, skbn);
sent += len;
}
kfree_skb(skb);
} else {
skb_queue_tail(&sk->sk_write_queue, skb);
sent = skb->len - header_len;
}
return sent;
}
/*
* This procedure is passed a buffer descriptor for an iframe. It builds
* the rest of the control part of the frame and then writes it out.
*/
static void x25_send_iframe(struct sock *sk, struct sk_buff *skb)
{
struct x25_sock *x25 = x25_sk(sk);
if (!skb)
return;
if (x25->neighbour->extended) {
skb->data[2] = (x25->vs << 1) & 0xFE;
skb->data[3] &= X25_EXT_M_BIT;
skb->data[3] |= (x25->vr << 1) & 0xFE;
} else {
skb->data[2] &= X25_STD_M_BIT;
skb->data[2] |= (x25->vs << 1) & 0x0E;
skb->data[2] |= (x25->vr << 5) & 0xE0;
}
x25_transmit_link(skb, x25->neighbour);
}
void x25_kick(struct sock *sk)
{
struct sk_buff *skb, *skbn;
unsigned short start, end;
int modulus;
struct x25_sock *x25 = x25_sk(sk);
if (x25->state != X25_STATE_3)
return;
/*
* Transmit interrupt data.
*/
if (skb_peek(&x25->interrupt_out_queue) != NULL &&
!test_and_set_bit(X25_INTERRUPT_FLAG, &x25->flags)) {
skb = skb_dequeue(&x25->interrupt_out_queue);
x25_transmit_link(skb, x25->neighbour);
}
if (x25->condition & X25_COND_PEER_RX_BUSY)
return;
if (!skb_peek(&sk->sk_write_queue))
return;
modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
start = skb_peek(&x25->ack_queue) ? x25->vs : x25->va;
end = (x25->va + x25->facilities.winsize_out) % modulus;
if (start == end)
return;
x25->vs = start;
/*
* Transmit data until either we're out of data to send or
* the window is full.
*/
skb = skb_dequeue(&sk->sk_write_queue);
do {
if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
skb_queue_head(&sk->sk_write_queue, skb);
break;
}
skb_set_owner_w(skbn, sk);
/*
* Transmit the frame copy.
*/
x25_send_iframe(sk, skbn);
x25->vs = (x25->vs + 1) % modulus;
/*
* Requeue the original data frame.
*/
skb_queue_tail(&x25->ack_queue, skb);
} while (x25->vs != end &&
(skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
x25->vl = x25->vr;
x25->condition &= ~X25_COND_ACK_PENDING;
x25_stop_timer(sk);
}
/*
* The following routines are taken from page 170 of the 7th ARRL Computer
* Networking Conference paper, as is the whole state machine.
*/
void x25_enquiry_response(struct sock *sk)
{
struct x25_sock *x25 = x25_sk(sk);
if (x25->condition & X25_COND_OWN_RX_BUSY)
x25_write_internal(sk, X25_RNR);
else
x25_write_internal(sk, X25_RR);
x25->vl = x25->vr;
x25->condition &= ~X25_COND_ACK_PENDING;
x25_stop_timer(sk);
}
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