netdev - [RFC PATCH V3 11/16] netback: print alert and bail when scratch space is not available.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1327934734-8908-12-git-send-email-wei.liu2@citrix.com>
Date:	Mon, 30 Jan 2012 14:45:29 +0000
From:	Wei Liu <wei.liu2@...rix.com>
To:	netdev@...r.kernel.org, xen-devel@...ts.xensource.com
CC:	ian.campbell@...rix.com, konrad.wilk@...cle.com,
	Wei Liu <wei.liu2@...rix.com>
Subject: [RFC PATCH V3 11/16] netback: print alert and bail when scratch space is not available.

CPU online event causes our callback to allocate scratch space for
this CPU, which may fail. The simplest and best action when NAPI or
kthread is scheduled on that CPU is to bail.

Signed-off-by: Wei Liu <wei.liu2@...rix.com>
---
 drivers/net/xen-netback/interface.c |    5 ++++-
 drivers/net/xen-netback/netback.c   |   17 +++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletions(-)

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index d7a7cd9..a5de556 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -69,6 +69,9 @@ static int xenvif_poll(struct napi_struct *napi, int budget)
 	struct xenvif *vif = container_of(napi, struct xenvif, napi);
 	int work_done = 0;
 
+	/* N.B.: work_done may be -ENOMEM, indicating scratch space on
+	 * this CPU is not usable. In this situation, we shutdown
+	 * NAPI. See __napi_complete check below.*/
 	work_done = xenvif_tx_action(vif, budget);
 
 	if (work_done < budget) {
@@ -78,7 +81,7 @@ static int xenvif_poll(struct napi_struct *napi, int budget)
 		local_irq_save(flag);
 
 		RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
-		if (!more_to_do)
+		if (!more_to_do || work_done < 0)
 			__napi_complete(napi);
 
 		local_irq_restore(flag);
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 2ac9b84..df63703 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -490,6 +490,15 @@ void xenvif_rx_action(struct xenvif *vif)
 		.meta  = m,
 	};
 
+	if (gco == NULL || m == NULL) {
+		put_cpu_var(grant_copy_op);
+		put_cpu_var(meta);
+		printk(KERN_ALERT "netback: CPU %x scratch space is not usable,"
+		       " not doing any TX work for vif%u.%u\n",
+		       smp_processor_id(), vif->domid, vif->handle);
+		return;
+	}
+
 	skb_queue_head_init(&rxq);
 
 	count = 0;
@@ -1290,6 +1299,14 @@ int xenvif_tx_action(struct xenvif *vif, int budget)
 
 	tco = get_cpu_var(tx_copy_ops);
 
+	if (tco == NULL) {
+		put_cpu_var(tx_copy_ops);
+		printk(KERN_ALERT "netback: CPU %x scratch space is not usable,"
+		       " not doing any RX work for vif%u.%u\n",
+		       smp_processor_id(), vif->domid, vif->handle);
+		return -ENOMEM;
+	}
+
 	nr_gops = xenvif_tx_build_gops(vif, tco);
 
 	if (nr_gops == 0) {
-- 
1.7.2.5

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html