diff mbox

slowpath warning

Message ID 201001261516.39057.lindner_marek@yahoo.de
State Superseded, archived
Headers show

Commit Message

Marek Lindner Jan. 26, 2010, 7:16 a.m. UTC
On Tuesday 26 January 2010 14:13:11 Linus Lüssing wrote:
> I'm now able to reproduce the second problem as well:
> Activating the vis-server on one node causes the vis-clients to
> throw this call trace with its slow path warning imediately.
> Nevertheless, vis output works anyway, clients are sending
> vis-packets and the server is drawing nice graphs.
> See the attachment for an example call trace.

Please try the attached patch and see if it helps.

Regards,
Marek

Comments

Linus Lüssing Jan. 27, 2010, 12:10 a.m. UTC | #1
Hi Marek,

nope, does not seem to work, still the same issue
I also tried it on my laptop here with the patch installed 
and it is a very similar call trace, although here it is 
send_vis_packets instead of vis_quit in the call trace.

Cheers, Linus

On Tue, Jan 26, 2010 at 03:16:38PM +0800, Marek Lindner wrote:
> On Tuesday 26 January 2010 14:13:11 Linus Lüssing wrote:
> > I'm now able to reproduce the second problem as well:
> > Activating the vis-server on one node causes the vis-clients to
> > throw this call trace with its slow path warning imediately.
> > Nevertheless, vis output works anyway, clients are sending
> > vis-packets and the server is drawing nice graphs.
> > See the attachment for an example call trace.
> 
> Please try the attached patch and see if it helps.
> 
> Regards,
> Marek

> diff --git a/batman-adv-kernelland/vis.c b/batman-adv-kernelland/vis.c
> index b118d1e..a6c235f 100644
> --- a/batman-adv-kernelland/vis.c
> +++ b/batman-adv-kernelland/vis.c
> @@ -405,6 +405,9 @@ static void purge_vis_packets(void)
>  {
>  	HASHIT(hashit);
>  	struct vis_info *info;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&vis_hash_lock, flags);
>  
>  	while (hash_iterate(vis_hash, &hashit)) {
>  		info = hashit.bucket->data;
> @@ -416,13 +419,17 @@ static void purge_vis_packets(void)
>  			free_info(info);
>  		}
>  	}
> +
> +	spin_unlock_irqrestore(&vis_hash_lock, flags);
>  }
>  
>  static void broadcast_vis_packet(struct vis_info *info, int packet_length)
>  {
>  	HASHIT(hashit);
>  	struct orig_node *orig_node;
> +	struct batman_if *batman_if;
>  	unsigned long flags;
> +	uint8_t dstaddr[ETH_ALEN];
>  
>  	spin_lock_irqsave(&orig_hash_lock, flags);
>  
> @@ -431,45 +438,60 @@ static void broadcast_vis_packet(struct vis_info *info, int packet_length)
>  		orig_node = hashit.bucket->data;
>  
>  		/* if it's a vis server and reachable, send it. */
> -		if (orig_node &&
> -		    (orig_node->flags & VIS_SERVER) &&
> -		    orig_node->batman_if &&
> -		    orig_node->router) {
> +		if ((!orig_node) || (!orig_node->batman_if) ||
> +		    (!orig_node->router))
> +			continue;
>  
> -			/* don't send it if we already received the packet from
> -			 * this node. */
> -			if (recv_list_is_in(&info->recv_list, orig_node->orig))
> -				continue;
> +		if (!(orig_node->flags & VIS_SERVER))
> +			continue;
>  
> -			memcpy(info->packet.target_orig,
> -			       orig_node->orig, ETH_ALEN);
> +		/* don't send it if we already received the packet from
> +		 * this node. */
> +		if (recv_list_is_in(&info->recv_list, orig_node->orig))
> +			continue;
>  
> -			send_raw_packet((unsigned char *) &info->packet,
> -					packet_length,
> -					orig_node->batman_if,
> -					orig_node->router->addr);
> -		}
> +		spin_unlock_irqrestore(&orig_hash_lock, flags);
> +
> +		memcpy(info->packet.target_orig, orig_node->orig, ETH_ALEN);
> +		batman_if = orig_node->batman_if;
> +		memcpy(dstaddr, orig_node->router->addr, ETH_ALEN);
> +
> +		send_raw_packet((unsigned char *)&info->packet,
> +				packet_length, batman_if, dstaddr);
> +
> +		spin_lock_irqsave(&orig_hash_lock, flags);
>  	}
> -	memcpy(info->packet.target_orig, broadcastAddr, ETH_ALEN);
> +
>  	spin_unlock_irqrestore(&orig_hash_lock, flags);
> +	memcpy(info->packet.target_orig, broadcastAddr, ETH_ALEN);
>  }
>  
>  static void unicast_vis_packet(struct vis_info *info, int packet_length)
>  {
>  	struct orig_node *orig_node;
> +	struct batman_if *batman_if;
>  	unsigned long flags;
> +	uint8_t dstaddr[ETH_ALEN];
>  
>  	spin_lock_irqsave(&orig_hash_lock, flags);
>  	orig_node = ((struct orig_node *)
>  		     hash_find(orig_hash, info->packet.target_orig));
>  
> -	if ((orig_node != NULL) &&
> -	    (orig_node->batman_if != NULL) &&
> -	    (orig_node->router != NULL)) {
> -		send_raw_packet((unsigned char *) &info->packet, packet_length,
> -				orig_node->batman_if,
> -				orig_node->router->addr);
> -	}
> +	if ((!orig_node) || (!orig_node->batman_if) || (!orig_node->router))
> +		goto out;
> +
> +	/* don't lock while sending the packets ... we therefore
> +	 * copy the required data before sending */
> +	batman_if = orig_node->batman_if;
> +	memcpy(dstaddr, orig_node->router->addr, ETH_ALEN);
> +	spin_unlock_irqrestore(&orig_hash_lock, flags);
> +
> +	send_raw_packet((unsigned char *)&info->packet,
> +			packet_length, batman_if, dstaddr);
> +
> +	return;
> +
> +out:
>  	spin_unlock_irqrestore(&orig_hash_lock, flags);
>  }
>  
> @@ -502,17 +524,18 @@ static void send_vis_packets(struct work_struct *work)
>  	struct vis_info *info, *temp;
>  	unsigned long flags;
>  
> -	spin_lock_irqsave(&vis_hash_lock, flags);
>  	purge_vis_packets();
>  
>  	if (generate_vis_packet() == 0)
>  		/* schedule if generation was successful */
>  		list_add_tail(&my_vis_info->send_list, &send_list);
>  
> +	spin_lock_irqsave(&vis_hash_lock, flags);
>  	list_for_each_entry_safe(info, temp, &send_list, send_list) {
>  		list_del_init(&info->send_list);
>  		send_vis_packet(info);
>  	}
> +
>  	spin_unlock_irqrestore(&vis_hash_lock, flags);
>  	start_vis_timer();
>  }
[22933.613178] ------------[ cut here ]------------
[22933.613199] WARNING: at /tmp/buildd/linux-2.6-2.6.31/debian/build/source_i386_none/kernel/softirq.c:143 _local_bh_enable_ip+0x41/0x97()
[22933.613206] Hardware name: ���������������
[22933.613211] Modules linked in: batman_adv isofs udf nvidia(P) ppdev lp parport sco bridge stp bnep rfcomm kvm_intel kvm acpi_cpufreq cpufreq_powersave cpufreq_conservative cpufreq_userspace cpufreq_stats l2cap nfsd exportfs nfs lockd fscache nfs_acl auth_rpcgss sunrpc fuse dm_snapshot dm_mirror dm_region_hash dm_log firewire_sbp2 loop snd_hda_codec_realtek snd_hda_intel snd_hda_codec arc4 ecb acer_wmi iwlagn snd_hwdep iwlcore snd_pcm_oss snd_mixer_oss snd_pcm mac80211 snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq snd_timer snd_seq_device uvcvideo videodev snd soundcore i2c_i801 cp210x v4l1_compat btusb snd_page_alloc cfg80211 v4l2_compat_ioctl32 psmouse bluetooth wmi serio_raw rfkill i2c_core usbserial evdev pcspkr ac processor button battery ext3 jbd mbcache sha256_generic cryptd aes_x86_64 aes_generic cbc dm_crypt dm_mod sd_mod crc_t10dif ide_cd_mod cdrom ata_generic ide_pci_generic ahci sdhci_pci sdhci uhci_hcd mmc_core libata tg3 led_class libphy firewire_ohci firewire_core crc_itu_t ricoh_mmc video output piix ide_core scsi_mod ehci_hcd intel_agp thermal fan thermal_sys [last unloaded: batman_adv]
[22933.613436] Pid: 14882, comm: bat_events Tainted: P           2.6.31-1-amd64 #1
[22933.613442] Call Trace:
[22933.613453]  [<ffffffff810503fa>] ? _local_bh_enable_ip+0x41/0x97
[22933.613462]  [<ffffffff810503fa>] ? _local_bh_enable_ip+0x41/0x97
[22933.613471]  [<ffffffff8104af08>] ? warn_slowpath_common+0x77/0xa3
[22933.613480]  [<ffffffff810503fa>] ? _local_bh_enable_ip+0x41/0x97
[22933.613490]  [<ffffffff812c821f>] ? run_filter+0x33/0x3a
[22933.613498]  [<ffffffff812c8c56>] ? packet_rcv+0xa9/0x2fb
[22933.613511]  [<ffffffff812389e5>] ? dev_hard_start_xmit+0x143/0x2ba
[22933.613521]  [<ffffffff8124ac7e>] ? __qdisc_run+0xe2/0x1ec
[22933.613529]  [<ffffffff81238e8f>] ? dev_queue_xmit+0x232/0x32c
[22933.613551]  [<ffffffffa0fe8945>] ? send_vis_packets+0x4f5/0x5d5 [batman_adv]
[22933.613571]  [<ffffffffa0fe8450>] ? send_vis_packets+0x0/0x5d5 [batman_adv]
[22933.613581]  [<ffffffff8105b43b>] ? worker_thread+0x174/0x211
[22933.613590]  [<ffffffff8105f39e>] ? autoremove_wake_function+0x0/0x2e
[22933.613599]  [<ffffffff8105b2c7>] ? worker_thread+0x0/0x211
[22933.613606]  [<ffffffff8105f042>] ? kthread+0x8b/0x93
[22933.613616]  [<ffffffff81011baa>] ? child_rip+0xa/0x20
[22933.613623]  [<ffffffff8105efb7>] ? kthread+0x0/0x93
[22933.613631]  [<ffffffff81011ba0>] ? child_rip+0x0/0x20
[22933.613636] ---[ end trace 1758b3e01bf5c445 ]---
Marek Lindner Jan. 28, 2010, 12:09 a.m. UTC | #2
Hi,

> nope, does not seem to work, still the same issue
> I also tried it on my laptop here with the patch installed 
> and it is a very similar call trace, although here it is 
> send_vis_packets instead of vis_quit in the call trace.

you should take the stack trace with a grain of salt. Stack tracing such an 
issue is a quite tricky thing, hence can not be fully trusted. Since the skb 
changes the code runs in interrupt context which probably introduced this bug. 
All previous warnings of this kind were related to holding a lock while 
sending packets. My patch unlocked the problematic orig_hash - maybe that was 
not enough ? By adding retrun statements at the beginning of the vis send 
function you might be able to get down to the problem.

Regards,
Marek
Andrew Lunn Jan. 28, 2010, 6:29 a.m. UTC | #3
On Thu, Jan 28, 2010 at 08:09:57AM +0800, Marek Lindner wrote:
> 
> Hi,
> 
> > nope, does not seem to work, still the same issue
> > I also tried it on my laptop here with the patch installed 
> > and it is a very similar call trace, although here it is 
> > send_vis_packets instead of vis_quit in the call trace.
> 
> you should take the stack trace with a grain of salt. Stack tracing such an 
> issue is a quite tricky thing, hence can not be fully trusted. Since the skb 
> changes the code runs in interrupt context which probably introduced this bug. 
> All previous warnings of this kind were related to holding a lock while 
> sending packets. My patch unlocked the problematic orig_hash - maybe that was 
> not enough ? By adding retrun statements at the beginning of the vis send 
> function you might be able to get down to the problem.

It might also be worth running lockdep on the code. Normally you don^t
need the actually lockup, you just need to execute the code path that
would lockup under whatever conditions are required for it to lockup.

      Andrew
diff mbox

Patch

diff --git a/batman-adv-kernelland/vis.c b/batman-adv-kernelland/vis.c
index b118d1e..a6c235f 100644
--- a/batman-adv-kernelland/vis.c
+++ b/batman-adv-kernelland/vis.c
@@ -405,6 +405,9 @@  static void purge_vis_packets(void)
 {
 	HASHIT(hashit);
 	struct vis_info *info;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vis_hash_lock, flags);
 
 	while (hash_iterate(vis_hash, &hashit)) {
 		info = hashit.bucket->data;
@@ -416,13 +419,17 @@  static void purge_vis_packets(void)
 			free_info(info);
 		}
 	}
+
+	spin_unlock_irqrestore(&vis_hash_lock, flags);
 }
 
 static void broadcast_vis_packet(struct vis_info *info, int packet_length)
 {
 	HASHIT(hashit);
 	struct orig_node *orig_node;
+	struct batman_if *batman_if;
 	unsigned long flags;
+	uint8_t dstaddr[ETH_ALEN];
 
 	spin_lock_irqsave(&orig_hash_lock, flags);
 
@@ -431,45 +438,60 @@  static void broadcast_vis_packet(struct vis_info *info, int packet_length)
 		orig_node = hashit.bucket->data;
 
 		/* if it's a vis server and reachable, send it. */
-		if (orig_node &&
-		    (orig_node->flags & VIS_SERVER) &&
-		    orig_node->batman_if &&
-		    orig_node->router) {
+		if ((!orig_node) || (!orig_node->batman_if) ||
+		    (!orig_node->router))
+			continue;
 
-			/* don't send it if we already received the packet from
-			 * this node. */
-			if (recv_list_is_in(&info->recv_list, orig_node->orig))
-				continue;
+		if (!(orig_node->flags & VIS_SERVER))
+			continue;
 
-			memcpy(info->packet.target_orig,
-			       orig_node->orig, ETH_ALEN);
+		/* don't send it if we already received the packet from
+		 * this node. */
+		if (recv_list_is_in(&info->recv_list, orig_node->orig))
+			continue;
 
-			send_raw_packet((unsigned char *) &info->packet,
-					packet_length,
-					orig_node->batman_if,
-					orig_node->router->addr);
-		}
+		spin_unlock_irqrestore(&orig_hash_lock, flags);
+
+		memcpy(info->packet.target_orig, orig_node->orig, ETH_ALEN);
+		batman_if = orig_node->batman_if;
+		memcpy(dstaddr, orig_node->router->addr, ETH_ALEN);
+
+		send_raw_packet((unsigned char *)&info->packet,
+				packet_length, batman_if, dstaddr);
+
+		spin_lock_irqsave(&orig_hash_lock, flags);
 	}
-	memcpy(info->packet.target_orig, broadcastAddr, ETH_ALEN);
+
 	spin_unlock_irqrestore(&orig_hash_lock, flags);
+	memcpy(info->packet.target_orig, broadcastAddr, ETH_ALEN);
 }
 
 static void unicast_vis_packet(struct vis_info *info, int packet_length)
 {
 	struct orig_node *orig_node;
+	struct batman_if *batman_if;
 	unsigned long flags;
+	uint8_t dstaddr[ETH_ALEN];
 
 	spin_lock_irqsave(&orig_hash_lock, flags);
 	orig_node = ((struct orig_node *)
 		     hash_find(orig_hash, info->packet.target_orig));
 
-	if ((orig_node != NULL) &&
-	    (orig_node->batman_if != NULL) &&
-	    (orig_node->router != NULL)) {
-		send_raw_packet((unsigned char *) &info->packet, packet_length,
-				orig_node->batman_if,
-				orig_node->router->addr);
-	}
+	if ((!orig_node) || (!orig_node->batman_if) || (!orig_node->router))
+		goto out;
+
+	/* don't lock while sending the packets ... we therefore
+	 * copy the required data before sending */
+	batman_if = orig_node->batman_if;
+	memcpy(dstaddr, orig_node->router->addr, ETH_ALEN);
+	spin_unlock_irqrestore(&orig_hash_lock, flags);
+
+	send_raw_packet((unsigned char *)&info->packet,
+			packet_length, batman_if, dstaddr);
+
+	return;
+
+out:
 	spin_unlock_irqrestore(&orig_hash_lock, flags);
 }
 
@@ -502,17 +524,18 @@  static void send_vis_packets(struct work_struct *work)
 	struct vis_info *info, *temp;
 	unsigned long flags;
 
-	spin_lock_irqsave(&vis_hash_lock, flags);
 	purge_vis_packets();
 
 	if (generate_vis_packet() == 0)
 		/* schedule if generation was successful */
 		list_add_tail(&my_vis_info->send_list, &send_list);
 
+	spin_lock_irqsave(&vis_hash_lock, flags);
 	list_for_each_entry_safe(info, temp, &send_list, send_list) {
 		list_del_init(&info->send_list);
 		send_vis_packet(info);
 	}
+
 	spin_unlock_irqrestore(&vis_hash_lock, flags);
 	start_vis_timer();
 }