[xen staging] x86/hpet: Fix return value of hpet_setup()

[patchbot@xxxxxxx]

commit 83736c567d6b64dbce98f251ca72e7870f556421
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Tue Dec 29 17:51:23 2020 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Thu Dec 31 16:19:00 2020 +0000

    x86/hpet: Fix return value of hpet_setup()
    
    hpet_setup() is idempotent if the rate has already been calculated, and
    returns the cached value.  However, this only works correctly when the 
return
    statements are identical.
    
    Use a sensibly named local variable, rather than a dead one with a bad name.
    
    Fixes: a60bb68219 ("x86/time: reduce rounding errors in calculations")
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/hpet.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/hpet.c b/xen/arch/x86/hpet.c
index a55e68e6f7..e6fab8acd8 100644
--- a/xen/arch/x86/hpet.c
+++ b/xen/arch/x86/hpet.c
@@ -759,7 +759,7 @@ u64 __init hpet_setup(void)
 {
     static u64 __initdata hpet_rate;
     u32 hpet_id, hpet_period;
-    unsigned int last;
+    unsigned int last, rem;
 
     if ( hpet_rate )
         return hpet_rate;
@@ -789,9 +789,11 @@ u64 __init hpet_setup(void)
     hpet_resume(hpet_boot_cfg);
 
     hpet_rate = 1000000000000000ULL; /* 10^15 */
-    last = do_div(hpet_rate, hpet_period);
+    rem = do_div(hpet_rate, hpet_period);
+    if ( (rem * 2) > hpet_period )
+        hpet_rate++;
 
-    return hpet_rate + (last * 2 > hpet_period);
+    return hpet_rate;
 }
 
 void hpet_resume(u32 *boot_cfg)
--
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