[tip:x86/urgent] x86 smpboot: Re-enable init_udelay= 0 by default on modern CPUs

[tip-bot for Len Brown]

Commit-ID:  656279a1f3b210cf48ccc572fd7c6b8e2250be77
Gitweb:     http://git.kernel.org/tip/656279a1f3b210cf48ccc572fd7c6b8e2250be77
Author:     Len Brown <len.brown@xxxxxxxxx>
AuthorDate: Sun, 22 Nov 2015 18:16:15 -0500
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Wed, 25 Nov 2015 23:17:48 +0100

x86 smpboot: Re-enable init_udelay=0 by default on modern CPUs

commit f1ccd249319e allowed the cmdline "cpu_init_udelay=" to work
with all values, including the default of 10000.

But in setting the default of 10000, it over-rode the code that sets
the delay 0 on modern processors.

Also, tidy up use of INT/UINT.

Fixes: f1ccd249319e "x86/smpboot: Fix cpu_init_udelay=10000 corner case boot parameter misbehavior"
Reported-by: Shane <shrybman@xxxxxxxxxxxx>
Signed-off-by: Len Brown <len.brown@xxxxxxxxx>
Cc: dparsons@xxxxxxxxxxxxx
Cc: stable@xxxxxxxxxx
Link: http://lkml.kernel.org/r/9082eb809ef40dad02db714759c7aaf618c518d4.1448232494.git.len.brown@xxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 arch/x86/kernel/smpboot.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 892ee2e5..fbabe4f 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -509,7 +509,7 @@ void __inquire_remote_apic(int apicid)
  */
 #define UDELAY_10MS_DEFAULT 10000
 
-static unsigned int init_udelay = INT_MAX;
+static unsigned int init_udelay = UINT_MAX;
 
 static int __init cpu_init_udelay(char *str)
 {
@@ -522,14 +522,15 @@ early_param("cpu_init_udelay", cpu_init_udelay);
 static void __init smp_quirk_init_udelay(void)
 {
 	/* if cmdline changed it from default, leave it alone */
-	if (init_udelay != INT_MAX)
+	if (init_udelay != UINT_MAX)
 		return;
 
 	/* if modern processor, use no delay */
 	if (((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) && (boot_cpu_data.x86 == 6)) ||
-	    ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) && (boot_cpu_data.x86 >= 0xF)))
+	    ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) && (boot_cpu_data.x86 >= 0xF))) {
 		init_udelay = 0;
-
+		return;
+	}
 	/* else, use legacy delay */
 	init_udelay = UDELAY_10MS_DEFAULT;
 }
--
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