On 14/11/13 09:35, Chen Gang wrote: > On 11/14/2013 05:18 PM, James Hogan wrote: >> On Thursday 14 November 2013 16:11:21 Chen Gang wrote: >>> Like another p?d_alloc(), pud_alloc() also may fail, so need check it. >>> >>> Signed-off-by: Chen Gang <[email protected]> >> >> NAK. >> >> pud_alloc folds to pud_offset on Meta so it cannot fail. >> > > If so, can pmd_alloc() be fail?
No. pmd_alloc folds to pmd_offset so it also cannot fail, and the existing !pmd check is dead code. The following would be better. Cheers James >From 85a386a9c7df666b1f438435be8a89581bc7e8b3 Mon Sep 17 00:00:00 2001 From: James Hogan <[email protected]> Date: Thu, 14 Nov 2013 10:14:37 +0000 Subject: [PATCH 1/1] metag: dma: remove dead code in dma_alloc_init() Meta has 2 levels of page table so the pmd folds into the pud which folds into the pgd. Therefore the !pmd check in dma_alloc_init() is dead code since it essentially checks whether: (init_mm->pgd + 0x770) == 0 Remove the check. Reported-by: Chen Gang <[email protected]> Signed-off-by: James Hogan <[email protected]> --- arch/metag/kernel/dma.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/arch/metag/kernel/dma.c b/arch/metag/kernel/dma.c index 8c00dedadc54..78205dbc2b86 100644 --- a/arch/metag/kernel/dma.c +++ b/arch/metag/kernel/dma.c @@ -401,11 +401,6 @@ static int __init dma_alloc_init(void) pgd = pgd_offset(&init_mm, CONSISTENT_START); pud = pud_alloc(&init_mm, pgd, CONSISTENT_START); pmd = pmd_alloc(&init_mm, pud, CONSISTENT_START); - if (!pmd) { - pr_err("%s: no pmd tables\n", __func__); - ret = -ENOMEM; - break; - } WARN_ON(!pmd_none(*pmd)); pte = pte_alloc_kernel(pmd, CONSISTENT_START); -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-metag" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
