[PATCH net 0/2] enic: Bug fixes

[PATCH net 0/2] enic: Bug fixes

[Govindarajulu Varadarajan]

This series fixes the following problem.

Please apply this to net.

Govindarajulu Varadarajan (2):
  enic: fix possible deadlock in enic_stop/ enic_rfs_flw_tbl_free
  enic: Do not call napi_disable when preemption is disabled.

 drivers/net/ethernet/cisco/enic/enic_clsf.c | 12 ++++++------
 drivers/net/ethernet/cisco/enic/enic_main.c |  4 ++--
 2 files changed, 8 insertions(+), 8 deletions(-)

-- 
2.1.0

[PATCH net 1/2] enic: fix possible deadlock in enic_stop/ enic_rfs_flw_tbl_free

[Govindarajulu Varadarajan]

The following warning is shown when spinlock debug is enabled.

This occurs when enic_flow_may_expire timer function is running and
enic_stop is called on same CPU.

Fix this by using spink_lock_bh().

=================================
[ INFO: inconsistent lock state ]
3.17.0-netnext-05504-g59f35b8 #268 Not tainted
---------------------------------
inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
ifconfig/443 [HC0[0]:SC0[0]:HE1:SE1] takes:
 (&(&enic->rfs_h.lock)->rlock){+.?...}, at:
enic_rfs_flw_tbl_free+0x34/0xd0 [enic]
{IN-SOFTIRQ-W} state was registered at:
  [<ffffffff810a25af>] __lock_acquire+0x83f/0x21c0
  [<ffffffff810a45f2>] lock_acquire+0xa2/0xd0
  [<ffffffff814913fc>] _raw_spin_lock+0x3c/0x80
  [<ffffffffa029c3d5>] enic_flow_may_expire+0x25/0x130[enic]
  [<ffffffff810bcd07>] call_timer_fn+0x77/0x100
  [<ffffffff810bd8e3>] run_timer_softirq+0x1e3/0x270
  [<ffffffff8105f9ae>] __do_softirq+0x14e/0x280
  [<ffffffff8105fdae>] irq_exit+0x8e/0xb0
  [<ffffffff8103da0f>] smp_apic_timer_interrupt+0x3f/0x50
  [<ffffffff81493742>] apic_timer_interrupt+0x72/0x80
  [<ffffffff81018143>] default_idle+0x13/0x20
  [<ffffffff81018a6a>] arch_cpu_idle+0xa/0x10
  [<ffffffff81097676>] cpu_startup_entry+0x2c6/0x330
  [<ffffffff8103b7ad>] start_secondary+0x21d/0x290
irq event stamp: 2997
hardirqs last  enabled at (2997): [<ffffffff81491865>] _raw_spin_unlock_irqrestore+0x65/0x90
hardirqs last disabled at (2996): [<ffffffff814915e6>] _raw_spin_lock_irqsave+0x26/0x90
softirqs last  enabled at (2968): [<ffffffff813b57a3>] dev_deactivate_many+0x213/0x260
softirqs last disabled at (2966): [<ffffffff813b5783>] dev_deactivate_many+0x1f3/0x260

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&(&enic->rfs_h.lock)->rlock);
  <Interrupt>
    lock(&(&enic->rfs_h.lock)->rlock);

 *** DEADLOCK ***

Reported-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Govindarajulu Varadarajan <_govind@gmx.com>
---
 drivers/net/ethernet/cisco/enic/enic_clsf.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/cisco/enic/enic_clsf.c b/drivers/net/ethernet/cisco/enic/enic_clsf.c
index 69dfd3c..0be6850 100644
--- a/drivers/net/ethernet/cisco/enic/enic_clsf.c
+++ b/drivers/net/ethernet/cisco/enic/enic_clsf.c
@@ -86,7 +86,7 @@ void enic_rfs_flw_tbl_free(struct enic *enic)
 	int i;
 
 	enic_rfs_timer_stop(enic);
-	spin_lock(&enic->rfs_h.lock);
+	spin_lock_bh(&enic->rfs_h.lock);
 	enic->rfs_h.free = 0;
 	for (i = 0; i < (1 << ENIC_RFS_FLW_BITSHIFT); i++) {
 		struct hlist_head *hhead;
@@ -100,7 +100,7 @@ void enic_rfs_flw_tbl_free(struct enic *enic)
 			kfree(n);
 		}
 	}
-	spin_unlock(&enic->rfs_h.lock);
+	spin_unlock_bh(&enic->rfs_h.lock);
 }
 
 struct enic_rfs_fltr_node *htbl_fltr_search(struct enic *enic, u16 fltr_id)
@@ -128,7 +128,7 @@ void enic_flow_may_expire(unsigned long data)
 	bool res;
 	int j;
 
-	spin_lock(&enic->rfs_h.lock);
+	spin_lock_bh(&enic->rfs_h.lock);
 	for (j = 0; j < ENIC_CLSF_EXPIRE_COUNT; j++) {
 		struct hlist_head *hhead;
 		struct hlist_node *tmp;
@@ -148,7 +148,7 @@ void enic_flow_may_expire(unsigned long data)
 			}
 		}
 	}
-	spin_unlock(&enic->rfs_h.lock);
+	spin_unlock_bh(&enic->rfs_h.lock);
 	mod_timer(&enic->rfs_h.rfs_may_expire, jiffies + HZ/4);
 }
 
@@ -183,7 +183,7 @@ int enic_rx_flow_steer(struct net_device *dev, const struct sk_buff *skb,
 		return -EPROTONOSUPPORT;
 
 	tbl_idx = skb_get_hash_raw(skb) & ENIC_RFS_FLW_MASK;
-	spin_lock(&enic->rfs_h.lock);
+	spin_lock_bh(&enic->rfs_h.lock);
 	n = htbl_key_search(&enic->rfs_h.ht_head[tbl_idx], &keys);
 
 	if (n) { /* entry already present  */
@@ -277,7 +277,7 @@ int enic_rx_flow_steer(struct net_device *dev, const struct sk_buff *skb,
 	}
 
 ret_unlock:
-	spin_unlock(&enic->rfs_h.lock);
+	spin_unlock_bh(&enic->rfs_h.lock);
 	return res;
 }
 
-- 
2.1.0

[PATCH net 2/2] enic: Do not call napi_disable when preemption is disabled.

[Govindarajulu Varadarajan]

In enic_stop, we disable preemption using local_bh_disable(). We disable
preemption to wait for busy_poll to finish.

napi_disable should not be called here as it might sleep.

Moving napi_disable() call out side of local_bh_disable.

BUG: sleeping function called from invalid context at include/linux/netdevice.h:477
in_atomic(): 1, irqs_disabled(): 0, pid: 443, name: ifconfig
INFO: lockdep is turned off.
Preemption disabled at:[<ffffffffa029c5c4>] enic_rfs_flw_tbl_free+0x34/0xd0 [enic]

CPU: 31 PID: 443 Comm: ifconfig Not tainted 3.17.0-netnext-05504-g59f35b8 #268
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
 ffff8800dac10000 ffff88020b8dfcb8 ffffffff8148a57c 0000000000000000
 ffff88020b8dfcd0 ffffffff8107e253 ffff8800dac12a40 ffff88020b8dfd10
 ffffffffa029305b ffff88020b8dfd48 ffff8800dac10000 ffff88020b8dfd48
Call Trace:
 [<ffffffff8148a57c>] dump_stack+0x4e/0x7a
 [<ffffffff8107e253>] __might_sleep+0x123/0x1a0
 [<ffffffffa029305b>] enic_stop+0xdb/0x4d0 [enic]
 [<ffffffff8138ed7d>] __dev_close_many+0x9d/0xf0
 [<ffffffff8138ef81>] __dev_close+0x31/0x50
 [<ffffffff813974a8>] __dev_change_flags+0x98/0x160
 [<ffffffff81397594>] dev_change_flags+0x24/0x60
 [<ffffffff814085fd>] devinet_ioctl+0x63d/0x710
 [<ffffffff81139c16>] ? might_fault+0x56/0xc0
 [<ffffffff81409ef5>] inet_ioctl+0x65/0x90
 [<ffffffff813768e0>] sock_do_ioctl+0x20/0x50
 [<ffffffff81376ebb>] sock_ioctl+0x20b/0x2e0
 [<ffffffff81197250>] do_vfs_ioctl+0x2e0/0x500
 [<ffffffff81492619>] ? sysret_check+0x22/0x5d
 [<ffffffff81285f23>] ? __this_cpu_preempt_check+0x13/0x20
 [<ffffffff8109fe19>] ? trace_hardirqs_on_caller+0x119/0x270
 [<ffffffff811974ac>] SyS_ioctl+0x3c/0x80
 [<ffffffff814925ed>] system_call_fastpath+0x1a/0x1f

Signed-off-by: Govindarajulu Varadarajan <_govind@gmx.com>
---
 drivers/net/ethernet/cisco/enic/enic_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/cisco/enic/enic_main.c b/drivers/net/ethernet/cisco/enic/enic_main.c
index 929bfe7..180e53f 100644
--- a/drivers/net/ethernet/cisco/enic/enic_main.c
+++ b/drivers/net/ethernet/cisco/enic/enic_main.c
@@ -1674,13 +1674,13 @@ static int enic_stop(struct net_device *netdev)
 
 	enic_dev_disable(enic);
 
-	local_bh_disable();
 	for (i = 0; i < enic->rq_count; i++) {
 		napi_disable(&enic->napi[i]);
+		local_bh_disable();
 		while (!enic_poll_lock_napi(&enic->rq[i]))
 			mdelay(1);
+		local_bh_enable();
 	}
-	local_bh_enable();
 
 	netif_carrier_off(netdev);
 	netif_tx_disable(netdev);
-- 
2.1.0

Re: [PATCH net 0/2] enic: Bug fixes

[David Miller]

From: Govindarajulu Varadarajan <_govind@gmx.com>
Date: Sun, 19 Oct 2014 14:20:26 +0530

> This series fixes the following problem.

??? This is a rather content free patch series header description
if you ask me.

> Please apply this to net.

Applied, thanks.