* [PATCH net] bnxt_en: Fix potential race condition in bnxt_tx_enable()
@ 2016-07-15 23:42 Florian Fainelli
2016-07-16 6:20 ` David Miller
2016-07-18 20:02 ` [PATCH net] bnxt_en: Remove locking around txr->dev_state Florian Fainelli
0 siblings, 2 replies; 6+ messages in thread
From: Florian Fainelli @ 2016-07-15 23:42 UTC (permalink / raw)
To: netdev; +Cc: davem, Florian Fainelli, Michael Chan, Jeffrey Huang, open list
txr->dev_state is always manipulated after acquiring the transmit queue
lock, except in bnxt_tx_enable(), which seems suspicious here, so also
acquire the transmit queue lock before changing the value.
Reported-by: coverity (CID 1339583)
Fixes: c0c050c58d840 ("bnxt_en: New Broadcom ethernet driver.")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
drivers/net/ethernet/broadcom/bnxt/bnxt.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index c777cde85ce4..904c2a8ece12 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -4599,7 +4599,9 @@ static void bnxt_tx_enable(struct bnxt *bp)
for (i = 0; i < bp->tx_nr_rings; i++) {
txr = &bp->tx_ring[i];
txq = netdev_get_tx_queue(bp->dev, i);
+ __netif_tx_lock(txq, smp_processor_id());
txr->dev_state = 0;
+ __netif_tx_unlock(txq);
}
netif_tx_wake_all_queues(bp->dev);
if (bp->link_info.link_up)
--
2.7.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH net] bnxt_en: Fix potential race condition in bnxt_tx_enable()
2016-07-15 23:42 [PATCH net] bnxt_en: Fix potential race condition in bnxt_tx_enable() Florian Fainelli
@ 2016-07-16 6:20 ` David Miller
2016-07-18 11:34 ` Michael Chan
2016-07-18 20:02 ` [PATCH net] bnxt_en: Remove locking around txr->dev_state Florian Fainelli
1 sibling, 1 reply; 6+ messages in thread
From: David Miller @ 2016-07-16 6:20 UTC (permalink / raw)
To: f.fainelli; +Cc: netdev, michael.chan, huangjw, linux-kernel
From: Florian Fainelli <f.fainelli@gmail.com>
Date: Fri, 15 Jul 2016 16:42:01 -0700
> @@ -4599,7 +4599,9 @@ static void bnxt_tx_enable(struct bnxt *bp)
> for (i = 0; i < bp->tx_nr_rings; i++) {
> txr = &bp->tx_ring[i];
> txq = netdev_get_tx_queue(bp->dev, i);
> + __netif_tx_lock(txq, smp_processor_id());
> txr->dev_state = 0;
> + __netif_tx_unlock(txq);
You're going to have to explain how this could possibly cause a
problem, because I'm pretty sure it can't.
Either the reader sees 0, or non-zero, in this value.
And adding locking around this assignment does not change that at all.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net] bnxt_en: Fix potential race condition in bnxt_tx_enable()
2016-07-16 6:20 ` David Miller
@ 2016-07-18 11:34 ` Michael Chan
0 siblings, 0 replies; 6+ messages in thread
From: Michael Chan @ 2016-07-18 11:34 UTC (permalink / raw)
To: David Miller; +Cc: f.fainelli, Netdev, Jeffrey Huang, linux-kernel
On Fri, Jul 15, 2016 at 11:20 PM, David Miller <davem@davemloft.net> wrote:
> From: Florian Fainelli <f.fainelli@gmail.com>
> Date: Fri, 15 Jul 2016 16:42:01 -0700
>
>> @@ -4599,7 +4599,9 @@ static void bnxt_tx_enable(struct bnxt *bp)
>> for (i = 0; i < bp->tx_nr_rings; i++) {
>> txr = &bp->tx_ring[i];
>> txq = netdev_get_tx_queue(bp->dev, i);
>> + __netif_tx_lock(txq, smp_processor_id());
>> txr->dev_state = 0;
>> + __netif_tx_unlock(txq);
>
> You're going to have to explain how this could possibly cause a
> problem, because I'm pretty sure it can't.
>
> Either the reader sees 0, or non-zero, in this value.
>
> And adding locking around this assignment does not change that at all.
Florian, I agree with David. The lock is not needed. The lock in
bnxt_tx_disable() is also unnecessary and should be removed. Thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH net] bnxt_en: Remove locking around txr->dev_state
2016-07-15 23:42 [PATCH net] bnxt_en: Fix potential race condition in bnxt_tx_enable() Florian Fainelli
2016-07-16 6:20 ` David Miller
@ 2016-07-18 20:02 ` Florian Fainelli
2016-07-18 20:06 ` Michael Chan
2016-07-20 2:22 ` David Miller
1 sibling, 2 replies; 6+ messages in thread
From: Florian Fainelli @ 2016-07-18 20:02 UTC (permalink / raw)
To: netdev; +Cc: davem, Florian Fainelli, Michael Chan, Jeffrey Huang, open list
txr->dev_state was not consistently manipulated with the acquisition of
the per-queue lock, after further inspection the lock does not seem
necessary, either the value is read as BNXT_DEV_STATE_CLOSING or 0.
Reported-by: coverity (CID 1339583)
Fixes: c0c050c58d840 ("bnxt_en: New Broadcom ethernet driver.")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
Changes in v2:
- remove locking in bnxt_tx_disable() as recommended by Michael
drivers/net/ethernet/broadcom/bnxt/bnxt.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index c777cde85ce4..15e1d1885919 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -4580,9 +4580,7 @@ static void bnxt_tx_disable(struct bnxt *bp)
for (i = 0; i < bp->tx_nr_rings; i++) {
txr = &bp->tx_ring[i];
txq = netdev_get_tx_queue(bp->dev, i);
- __netif_tx_lock(txq, smp_processor_id());
txr->dev_state = BNXT_DEV_STATE_CLOSING;
- __netif_tx_unlock(txq);
}
}
/* Stop all TX queues */
--
2.7.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH net] bnxt_en: Remove locking around txr->dev_state
2016-07-18 20:02 ` [PATCH net] bnxt_en: Remove locking around txr->dev_state Florian Fainelli
@ 2016-07-18 20:06 ` Michael Chan
2016-07-20 2:22 ` David Miller
1 sibling, 0 replies; 6+ messages in thread
From: Michael Chan @ 2016-07-18 20:06 UTC (permalink / raw)
To: Florian Fainelli; +Cc: Netdev, David Miller, Jeffrey Huang, open list
On Mon, Jul 18, 2016 at 1:02 PM, Florian Fainelli <f.fainelli@gmail.com> wrote:
> txr->dev_state was not consistently manipulated with the acquisition of
> the per-queue lock, after further inspection the lock does not seem
> necessary, either the value is read as BNXT_DEV_STATE_CLOSING or 0.
>
> Reported-by: coverity (CID 1339583)
> Fixes: c0c050c58d840 ("bnxt_en: New Broadcom ethernet driver.")
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Thanks Florian.
Acked-by: Michael Chan <michael.chan@broadcom.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net] bnxt_en: Remove locking around txr->dev_state
2016-07-18 20:02 ` [PATCH net] bnxt_en: Remove locking around txr->dev_state Florian Fainelli
2016-07-18 20:06 ` Michael Chan
@ 2016-07-20 2:22 ` David Miller
1 sibling, 0 replies; 6+ messages in thread
From: David Miller @ 2016-07-20 2:22 UTC (permalink / raw)
To: f.fainelli; +Cc: netdev, michael.chan, huangjw, linux-kernel
From: Florian Fainelli <f.fainelli@gmail.com>
Date: Mon, 18 Jul 2016 13:02:47 -0700
> txr->dev_state was not consistently manipulated with the acquisition of
> the per-queue lock, after further inspection the lock does not seem
> necessary, either the value is read as BNXT_DEV_STATE_CLOSING or 0.
>
> Reported-by: coverity (CID 1339583)
> Fixes: c0c050c58d840 ("bnxt_en: New Broadcom ethernet driver.")
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---
> Changes in v2:
>
> - remove locking in bnxt_tx_disable() as recommended by Michael
Applied to net-next, thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-07-20 2:23 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2016-07-15 23:42 [PATCH net] bnxt_en: Fix potential race condition in bnxt_tx_enable() Florian Fainelli
2016-07-16 6:20 ` David Miller
2016-07-18 11:34 ` Michael Chan
2016-07-18 20:02 ` [PATCH net] bnxt_en: Remove locking around txr->dev_state Florian Fainelli
2016-07-18 20:06 ` Michael Chan
2016-07-20 2:22 ` David Miller
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