linux-kernel - Re: [PATCH 2/2] staging: greybus: refactor arche_platform_wd

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Date:   Mon, 3 Apr 2023 18:23:03 +0300
From:   Dan Carpenter <error27@...il.com>
To:     Khadija Kamran <kamrankhadijadj@...il.com>
Cc:     outreachy@...ts.linux.dev, hvaibhav.linux@...il.com,
        johan@...nel.org, elder@...nel.org, gregkh@...uxfoundation.org,
        greybus-dev@...ts.linaro.org, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org,
        Alison Schofield <alison.schofield@...el.com>
Subject: Re: [PATCH 2/2] staging: greybus: refactor arche_platform_wd_irq()

On Mon, Apr 03, 2023 at 07:29:36AM +0300, Dan Carpenter wrote:
> > > This checks that we are not in WD_STATE_COLDBOOT_START state.  How are
> > > we going to be in COLDBOOT if we are in INIT?  Is this changing in the
> > > background?  Can this check be removed?

It turned out the answer was yes, it can be removed.

> Also if stuff is changing in the background and there is no way the
> locking is correct.

The locking is correct.  Take a look at it.

We are holding the &arche_pdata->wake_lock in arche_platform_wd_irq()
and every place that calls arche_platform_set_wake_detect_state() takes
that lock first.  So it can't change in the background.

Delete the check like so.

regards,
dan carpenter

diff --git a/drivers/staging/greybus/arche-platform.c b/drivers/staging/greybus/arche-platform.c
index fcbd5f71eff2..4cca45ee70b3 100644
--- a/drivers/staging/greybus/arche-platform.c
+++ b/drivers/staging/greybus/arche-platform.c
@@ -172,18 +172,11 @@ static irqreturn_t arche_platform_wd_irq(int irq, void *devid)
 				arche_platform_set_wake_detect_state(arche_pdata,
 								     WD_STATE_IDLE);
 			} else {
-				/*
-				 * Check we are not in middle of irq thread
-				 * already
-				 */
-				if (arche_pdata->wake_detect_state !=
-						WD_STATE_COLDBOOT_START) {
-					arche_platform_set_wake_detect_state(arche_pdata,
-									     WD_STATE_COLDBOOT_TRIG);
-					spin_unlock_irqrestore(&arche_pdata->wake_lock,
-							       flags);
-					return IRQ_WAKE_THREAD;
-				}
+				arche_platform_set_wake_detect_state(arche_pdata,
+								     WD_STATE_COLDBOOT_TRIG);
+				spin_unlock_irqrestore(&arche_pdata->wake_lock,
+						       flags);
+				return IRQ_WAKE_THREAD;
 			}
 		}
 	} else {