Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265060AbUFMN3f (ORCPT ); Sun, 13 Jun 2004 09:29:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265065AbUFMN3f (ORCPT ); Sun, 13 Jun 2004 09:29:35 -0400 Received: from h-68-165-86-241.dllatx37.covad.net ([68.165.86.241]:36915 "EHLO sol.microgate.com") by vger.kernel.org with ESMTP id S265060AbUFMN3Y (ORCPT ); Sun, 13 Jun 2004 09:29:24 -0400 Subject: Re: [PATCH][RFC] 2.6.6 tty_io.c hangup locking From: Paul Fulghum To: Jurjen Oskam Cc: linux-kernel@vger.kernel.org In-Reply-To: <20040613090543.GA29699@quadpro.stupendous.org> References: <20040527174509.GA1654@quadpro.stupendous.org> <1085769769.2106.23.camel@deimos.microgate.com> <20040613090543.GA29699@quadpro.stupendous.org> Content-Type: text/plain Message-Id: <1087133357.16761.11.camel@at2.pipehead.org> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.5 (1.4.5-7) Date: Sun, 13 Jun 2004 08:29:17 -0500 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9556 Lines: 300 On Sun, 2004-06-13 at 04:05, Jurjen Oskam wrote: > On Fri, May 28, 2004 at 01:42:50PM -0500, Paul Fulghum wrote: > > > The following patch removes unnecessary disabling of > > interrupts when processing hangup for tty devices. > > > > This was introduced way back in August 1998 > > with patch 2.1.115 when the original hangup processing was > > changed from cli/sti to lock_kernel()/unlock_kernel(). > > I applied this patch to vanilla 2.2.5, and have been running with it > for a week or two. During that time, I frequently used PPP. For testing, I > interrupted the connection when sending and/or receiving data. > > I didn't experience any problems whatsoever. Could I persuade you to also try this patch for ppp_synctty.c? If I remember correctly, you were using this module for PPPoE. It also fixes the softirq warning, but from a different angle. The tty_io.c patch will not be accepted until tty locking is completely reworked (which won't happen anytime soon). The patch below mirrors changes to ppp_async.c which have already been accepted. The ppp_synctty patch also fixes some callbacks to allow calls from hard interrupt context. I have been banging on it for a week with no problems. So, if possible, revert the tty_io.c patch, apply this one, and continue your testing. Thanks, Paul --- linux-2.6.6/drivers/net/ppp_synctty.c 2004-04-03 21:36:57.000000000 -0600 +++ linux-2.6.6-mg1/drivers/net/ppp_synctty.c 2004-06-02 15:01:35.177725315 -0500 @@ -65,7 +65,9 @@ struct sk_buff *tpkt; unsigned long last_xmit; - struct sk_buff *rpkt; + struct sk_buff_head rqueue; + + struct tasklet_struct tsk; atomic_t refcnt; struct semaphore dead_sem; @@ -88,6 +90,7 @@ static int ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb); static int ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg); +static void ppp_sync_process(unsigned long arg); static int ppp_sync_push(struct syncppp *ap); static void ppp_sync_flush_output(struct syncppp *ap); static void ppp_sync_input(struct syncppp *ap, const unsigned char *buf, @@ -217,6 +220,9 @@ ap->xaccm[3] = 0x60000000U; ap->raccm = ~0U; + skb_queue_head_init(&ap->rqueue); + tasklet_init(&ap->tsk, ppp_sync_process, (unsigned long) ap); + atomic_set(&ap->refcnt, 1); init_MUTEX_LOCKED(&ap->dead_sem); @@ -267,10 +273,10 @@ */ if (!atomic_dec_and_test(&ap->refcnt)) down(&ap->dead_sem); + tasklet_kill(&ap->tsk); ppp_unregister_channel(&ap->chan); - if (ap->rpkt != 0) - kfree_skb(ap->rpkt); + skb_queue_purge(&ap->rqueue); if (ap->tpkt != 0) kfree_skb(ap->tpkt); kfree(ap); @@ -369,17 +375,24 @@ return 65535; } +/* + * This can now be called from hard interrupt level as well + * as soft interrupt level or mainline. + */ static void ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf, - char *flags, int count) + char *cflags, int count) { struct syncppp *ap = sp_get(tty); + unsigned long flags; if (ap == 0) return; - spin_lock_bh(&ap->recv_lock); - ppp_sync_input(ap, buf, flags, count); - spin_unlock_bh(&ap->recv_lock); + spin_lock_irqsave(&ap->recv_lock, flags); + ppp_sync_input(ap, buf, cflags, count); + spin_unlock_irqrestore(&ap->recv_lock, flags); + if (skb_queue_len(&ap->rqueue)) + tasklet_schedule(&ap->tsk); sp_put(ap); if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) && tty->driver->unthrottle) @@ -394,8 +407,8 @@ clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); if (ap == 0) return; - if (ppp_sync_push(ap)) - ppp_output_wakeup(&ap->chan); + set_bit(XMIT_WAKEUP, &ap->xmit_flags); + tasklet_schedule(&ap->tsk); sp_put(ap); } @@ -449,9 +462,9 @@ if (get_user(val, (int *) arg)) break; ap->flags = val & ~SC_RCV_BITS; - spin_lock_bh(&ap->recv_lock); + spin_lock_irq(&ap->recv_lock); ap->rbits = val & SC_RCV_BITS; - spin_unlock_bh(&ap->recv_lock); + spin_unlock_irq(&ap->recv_lock); err = 0; break; @@ -512,6 +525,32 @@ } /* + * This is called at softirq level to deliver received packets + * to the ppp_generic code, and to tell the ppp_generic code + * if we can accept more output now. + */ +static void ppp_sync_process(unsigned long arg) +{ + struct syncppp *ap = (struct syncppp *) arg; + struct sk_buff *skb; + + /* process received packets */ + while ((skb = skb_dequeue(&ap->rqueue)) != NULL) { + if (skb->len == 0) { + /* zero length buffers indicate error */ + ppp_input_error(&ap->chan, 0); + kfree_skb(skb); + } + else + ppp_input(&ap->chan, skb); + } + + /* try to push more stuff out */ + if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_sync_push(ap)) + ppp_output_wakeup(&ap->chan); +} + +/* * Procedures for encapsulation and framing. */ @@ -600,7 +639,6 @@ struct tty_struct *tty = ap->tty; int tty_stuffed = 0; - set_bit(XMIT_WAKEUP, &ap->xmit_flags); if (!spin_trylock_bh(&ap->xmit_lock)) return 0; for (;;) { @@ -667,15 +705,44 @@ * Receive-side routines. */ -static inline void -process_input_packet(struct syncppp *ap) +/* called when the tty driver has data for us. + * + * Data is frame oriented: each call to ppp_sync_input is considered + * a whole frame. If the 1st flag byte is non-zero then the whole + * frame is considered to be in error and is tossed. + */ +static void +ppp_sync_input(struct syncppp *ap, const unsigned char *buf, + char *flags, int count) { struct sk_buff *skb; unsigned char *p; - int code = 0; - skb = ap->rpkt; - ap->rpkt = 0; + if (count == 0) + return; + + if (ap->flags & SC_LOG_INPKT) + ppp_print_buffer ("receive buffer", buf, count); + + /* stuff the chars in the skb */ + if ((skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2)) == 0) { + printk(KERN_ERR "PPPsync: no memory (input pkt)\n"); + goto err; + } + /* Try to get the payload 4-byte aligned */ + if (buf[0] != PPP_ALLSTATIONS) + skb_reserve(skb, 2 + (buf[0] & 1)); + + if (flags != 0 && *flags) { + /* error flag set, ignore frame */ + goto err; + } else if (count > skb_tailroom(skb)) { + /* packet overflowed MRU */ + goto err; + } + + p = skb_put(skb, count); + memcpy(p, buf, count); /* strip address/control field if present */ p = skb->data; @@ -693,59 +760,15 @@ } else if (skb->len < 2) goto err; - /* pass to generic layer */ - ppp_input(&ap->chan, skb); + /* queue the frame to be processed */ + skb_queue_tail(&ap->rqueue, skb); return; - err: - kfree_skb(skb); - ppp_input_error(&ap->chan, code); -} - -/* called when the tty driver has data for us. - * - * Data is frame oriented: each call to ppp_sync_input is considered - * a whole frame. If the 1st flag byte is non-zero then the whole - * frame is considered to be in error and is tossed. - */ -static void -ppp_sync_input(struct syncppp *ap, const unsigned char *buf, - char *flags, int count) -{ - struct sk_buff *skb; - unsigned char *sp; - - if (count == 0) - return; - - /* if flag set, then error, ignore frame */ - if (flags != 0 && *flags) { - ppp_input_error(&ap->chan, *flags); - return; - } - - if (ap->flags & SC_LOG_INPKT) - ppp_print_buffer ("receive buffer", buf, count); - - /* stuff the chars in the skb */ - if ((skb = ap->rpkt) == 0) { - if ((skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2)) == 0) { - printk(KERN_ERR "PPPsync: no memory (input pkt)\n"); - ppp_input_error(&ap->chan, 0); - return; - } - /* Try to get the payload 4-byte aligned */ - if (buf[0] != PPP_ALLSTATIONS) - skb_reserve(skb, 2 + (buf[0] & 1)); - ap->rpkt = skb; - } - if (count > skb_tailroom(skb)) { - /* packet overflowed MRU */ - ppp_input_error(&ap->chan, 1); - } else { - sp = skb_put(skb, count); - memcpy(sp, buf, count); - process_input_packet(ap); +err: + /* queue zero length packet as error indication */ + if (skb || (skb = dev_alloc_skb(0))) { + skb_trim(skb, 0); + skb_queue_tail(&ap->rqueue, skb); } } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/