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Message-ID: <1364408379-4353-1-git-send-email-yuvalmin@broadcom.com>
Date:	Wed, 27 Mar 2013 20:19:39 +0200
From:	"Yuval Mintz" <yuvalmin@...adcom.com>
To:	davem@...emloft.net, netdev@...r.kernel.org
cc:	"Yuval Mintz" <yuvalmin@...adcom.com>,
	"Ariel Elior" <ariele@...adcom.com>,
	"Eilon Greenstein" <eilong@...adcom.com>
Subject: [PATCH net-next] bnx2x: handle spurious interrupts

In scenarios in which a previous driver was removed without proper cleanup
(e.g., kdump), it is possible for the chip to generate an interrupt without
any apparent reason once interrupts are enabled.

This patch causes the driver to ignore any interrupt which arrives in an
inappropriate time, i.e., when the driver has not yet properly configured
its interrupt routines.

Signed-off-by: Yuval Mintz <yuvalmin@...adcom.com>
Signed-off-by: Ariel Elior <ariele@...adcom.com>
Signed-off-by: Eilon Greenstein <eilong@...adcom.com>
---
Hi Dave,

This was previously sent as part of a patch series - which you rejected due
to this patch. As the merge window opened the following day, I did not
argue on behalf of this patch (but I intend to do so now).

Your issue with the patch was that we've encountered a NULL pointer dereference
once said interrupt was generated, as bnx2x requests the IRQ from the kernel
prior to the initialization of all structs required for its handling.

However, my claim is that the 2 issues are orthogonal -
Perhaps this area in the bnx2x needs to be changed (even though no interrupts
should be generated until all structs are initialized), but the behaviour
added in current patch would still be unchanged.

Since the interrupt is unintentional, the proper driver behaviour should still
be to ignore it, as ACKing the HW for it might be harmful.
Since the driver must request the IRQ prior to enabling HW generation of
interrupts, it would still need to ignore every interrupt arriving during that
interval.

Thanks,
Yuval
---
 drivers/net/ethernet/broadcom/bnx2x/bnx2x.h      |    1 +
 drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c  |   11 +++++++++++
 drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c |    3 +++
 drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c |    3 ++-
 4 files changed, 17 insertions(+), 1 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h b/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
index e4605a9..3e26eb5 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
@@ -1379,6 +1379,7 @@ struct bnx2x {
 #define USING_SINGLE_MSIX_FLAG		(1 << 20)
 #define BC_SUPPORTS_DCBX_MSG_NON_PMF	(1 << 21)
 #define IS_VF_FLAG			(1 << 22)
+#define INTERRUPTS_ENABLED_FLAG	(1 << 23)
 
 #define BP_NOMCP(bp)			((bp)->flags & NO_MCP_FLAG)
 
diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
index ecac04a3..525c2b5 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
@@ -1037,6 +1037,17 @@ static irqreturn_t bnx2x_msix_fp_int(int irq, void *fp_cookie)
 	DP(NETIF_MSG_INTR,
 	   "got an MSI-X interrupt on IDX:SB [fp %d fw_sd %d igusb %d]\n",
 	   fp->index, fp->fw_sb_id, fp->igu_sb_id);
+
+	/* It's possible for a spurious interrupt to be received, if the
+	 * driver was loaded above a previous configured function (e.g., kdump).
+	 * We simply ignore such interrupts.
+	 */
+	if (unlikely(!(bp->flags & INTERRUPTS_ENABLED_FLAG))) {
+		WARN_ONCE(1, "%s: Got Spurious interrupts",
+			  bp->dev ? bp->dev->name : "?");
+		return IRQ_HANDLED;
+	}
+
 	bnx2x_ack_sb(bp, fp->igu_sb_id, USTORM_ID, 0, IGU_INT_DISABLE, 0);
 
 #ifdef BNX2X_STOP_ON_ERROR
diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
index c4daee1..1776b8b 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
@@ -868,6 +868,7 @@ static void bnx2x_int_disable(struct bnx2x *bp)
 		bnx2x_hc_int_disable(bp);
 	else
 		bnx2x_igu_int_disable(bp);
+	bp->flags &= ~INTERRUPTS_ENABLED_FLAG;
 }
 
 void bnx2x_panic_dump(struct bnx2x *bp, bool disable_int)
@@ -1607,6 +1608,8 @@ static void bnx2x_igu_int_enable(struct bnx2x *bp)
 
 void bnx2x_int_enable(struct bnx2x *bp)
 {
+	bp->flags |= INTERRUPTS_ENABLED_FLAG;
+
 	if (bp->common.int_block == INT_BLOCK_HC)
 		bnx2x_hc_int_enable(bp);
 	else
diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c
index 3624612..df9209e 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c
@@ -268,7 +268,8 @@ int bnx2x_vfpf_acquire(struct bnx2x *bp, u8 tx_count, u8 rx_count)
 	bp->mf_mode = 0;
 	bp->common.flash_size = 0;
 	bp->flags |=
-		NO_WOL_FLAG | NO_ISCSI_OOO_FLAG | NO_ISCSI_FLAG | NO_FCOE_FLAG;
+		NO_WOL_FLAG | NO_ISCSI_OOO_FLAG | NO_ISCSI_FLAG | NO_FCOE_FLAG |
+		INTERRUPTS_ENABLED_FLAG;
 	bp->igu_sb_cnt = 1;
 	bp->igu_base_sb = bp->acquire_resp.resc.hw_sbs[0].hw_sb_id;
 	strlcpy(bp->fw_ver, bp->acquire_resp.pfdev_info.fw_ver,
-- 
1.7.9.GIT


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