linux-kernel - [RFC][PATCH] MIPS: Use pagefault_{dis,en}able for k{,un}map

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Message-ID: <20130910113322.GE31370@twins.programming.kicks-ass.net>
Date:	Tue, 10 Sep 2013 13:33:22 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	ralf@...ux-mips.org
Cc:	linux-kernel@...r.kernel.org, linux-mips@...ux-mips.org
Subject: [RFC][PATCH] MIPS: Use pagefault_{dis,en}able for k{,un}map_coherent

Hi Ralf,

I was poking about the preempt_count muck and stumbled upon this..

Should you be using the pagefault_*() methods here?

--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -124,7 +124,7 @@ void *kmap_coherent(struct page *page, u
 
 	BUG_ON(Page_dcache_dirty(page));
 
-	inc_preempt_count();
+	pagefault_disable();
 	idx = (addr >> PAGE_SHIFT) & (FIX_N_COLOURS - 1);
 #ifdef CONFIG_MIPS_MT_SMTC
 	idx += FIX_N_COLOURS * smp_processor_id() +
@@ -193,8 +193,7 @@ void kunmap_coherent(void)
 	write_c0_entryhi(old_ctx);
 	EXIT_CRITICAL(flags);
 #endif
-	dec_preempt_count();
-	preempt_check_resched();
+	pagefault_enable();
 }
 
 void copy_user_highpage(struct page *to, struct page *from,
--
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