linux-kernel - Re: [PATCH 1/10] safe_apic_wait_icr_idle

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Date:	Wed, 25 Apr 2007 22:55:01 +1000
From:	Keith Owens <kaos@....com.au>
To:	Fernando Luis Vázquez Cao 
	<fernando@....ntt.co.jp>
cc:	"Eric W. Biederman" <ebiederm@...ssion.com>, horms@...ge.net.au,
	kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
	ak@...e.de, vgoyal@...ibm.com, mbligh@...gle.com,
	akpm@...ux-foundation.org
Subject: Re: [PATCH 1/10] safe_apic_wait_icr_idle - i386 

Fernando Luis =?ISO-8859-1?Q?V=E1zquez?= Cao (on Wed, 25 Apr 2007 20:13:28 +0900) wrote:
>+static __inline__ unsigned long safe_apic_wait_icr_idle(void)
>+{
>+	unsigned long send_status;
>+	int timeout;
>+
>+	timeout = 0;
>+	do {
>+		udelay(100);
>+		send_status = apic_read(APIC_ICR) & APIC_ICR_BUSY;
>+	} while (send_status && (timeout++ < 1000));
>+
>+	return send_status;
>+}
>+

safe_apic_wait_icr_idle() as coded guarantees a minimum 100 usec delay
before sending the IPI, this extra delay is unnecessary.  Change it to

	do {
		send_status = apic_read(APIC_ICR) & APIC_ICR_BUSY;
		if (send_status)
			break;
		udelay(100);
	} while (timeout++ < 1000);

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