linux-kernel - RE: [PATCH] USB/host: Cleanup unneccessary irq disable code

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Message-ID: <27240C0AC20F114CBF8149A2696CBE4A178037@SHSMSX101.ccr.corp.intel.com>
Date:	Thu, 6 Sep 2012 01:22:23 +0000
From:	"Liu, Chuansheng" <chuansheng.liu@...el.com>
To:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"stern@...land.harvard.edu" <stern@...land.harvard.edu>,
	"tglx@...utronix.de" <tglx@...utronix.de>
Subject: RE: [PATCH] USB/host: Cleanup unneccessary irq disable code

> > From: liu chuansheng <chuansheng.liu@...el.com>
> > Subject: [PATCH] USB/host: Cleanup unneccessary irq disable code
> 
> Why is this in the patch?
> 
> Please resend it in a format that I do not have to manually edit the patch.
> 
> greg k-h
Thanks your teaching, resend again.


Because the IRQF_DISABLED as the flag is now a NOOP and has been
deprecated and in hardirq context the interrupt is disabled.

so in usb/host code:
Removing the usage of flag IRQF_DISABLED;
Removing the calling local_irq save/restore actions in irq
handler usb_hcd_irq();

Signed-off-by: liu chuansheng <chuansheng.liu@...el.com>
---
 drivers/usb/core/hcd.c       |   15 ---------------
 drivers/usb/host/ehci-ls1x.c |    2 +-
 drivers/usb/host/ohci-xls.c  |    2 +-
 3 files changed, 2 insertions(+), 17 deletions(-)

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index bc84106..f84ddea 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -2153,15 +2153,8 @@ EXPORT_SYMBOL_GPL(usb_bus_start_enum);
 irqreturn_t usb_hcd_irq (int irq, void *__hcd)
 {
        struct usb_hcd          *hcd = __hcd;
-       unsigned long           flags;
        irqreturn_t             rc;
 
-       /* IRQF_DISABLED doesn't work correctly with shared IRQs
-        * when the first handler doesn't use it.  So let's just
-        * assume it's never used.
-        */
-       local_irq_save(flags);
-
        if (unlikely(HCD_DEAD(hcd) || !HCD_HW_ACCESSIBLE(hcd)))
                rc = IRQ_NONE;
        else if (hcd->driver->irq(hcd) == IRQ_NONE)
@@ -2169,7 +2162,6 @@ irqreturn_t usb_hcd_irq (int irq, void *__hcd)
        else
                rc = IRQ_HANDLED;
 
-       local_irq_restore(flags);
        return rc;
 }
 EXPORT_SYMBOL_GPL(usb_hcd_irq);
@@ -2358,13 +2350,6 @@ static int usb_hcd_request_irqs(struct usb_hcd *hcd,
 
        if (hcd->driver->irq) {
 
-               /* IRQF_DISABLED doesn't work as advertised when used together
-                * with IRQF_SHARED. As usb_hcd_irq() will always disable
-                * interrupts we can remove it here.
-                */
-               if (irqflags & IRQF_SHARED)
-                       irqflags &= ~IRQF_DISABLED;
-
                snprintf(hcd->irq_descr, sizeof(hcd->irq_descr), "%s:usb%d",
                                hcd->driver->description, hcd->self.busnum);
                retval = request_irq(irqnum, &usb_hcd_irq, irqflags,
diff --git a/drivers/usb/host/ehci-ls1x.c b/drivers/usb/host/ehci-ls1x.c
index a283e59..425cb4a 100644
--- a/drivers/usb/host/ehci-ls1x.c
+++ b/drivers/usb/host/ehci-ls1x.c
@@ -119,7 +119,7 @@ static int ehci_hcd_ls1x_probe(struct platform_device *pdev)
                goto err_release_region;
        }
 
-       ret = usb_add_hcd(hcd, irq, IRQF_DISABLED | IRQF_SHARED);
+       ret = usb_add_hcd(hcd, irq, IRQF_SHARED);
        if (ret)
                goto err_iounmap;
 
diff --git a/drivers/usb/host/ohci-xls.c b/drivers/usb/host/ohci-xls.c
index 41e378f..84201cd 100644
--- a/drivers/usb/host/ohci-xls.c
+++ b/drivers/usb/host/ohci-xls.c
@@ -56,7 +56,7 @@ static int ohci_xls_probe_internal(const struct hc_driver *driver,
                goto err3;
        }
 
-       retval = usb_add_hcd(hcd, irq, IRQF_DISABLED | IRQF_SHARED);
+       retval = usb_add_hcd(hcd, irq, IRQF_SHARED);
        if (retval != 0)
                goto err4;
        return retval;
-- 
1.7.0.4
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