[patch 0/1]pat: remove redundant condition check - Kernel

This is a discussion on [patch 0/1]pat: remove redundant condition check - Kernel ; On file pat.c, if (start start), it also means (start entry->end). This patch removes redundant condition check. Signed-off-by: bibo.mao@gmail.com thanks bibo,mao ------------------------------------------------------ diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 2a50e0f..12cac5e 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -305,27 +305,6 @@ int reserve_memtype(u64 start, ...

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Thread: [patch 0/1]pat: remove redundant condition check

  1. [patch 0/1]pat: remove redundant condition check

    On file pat.c, if (start <= entry->start), it also means (start <
    entry->end). This patch removes
    redundant condition check.

    Signed-off-by: bibo.mao@gmail.com
    thanks
    bibo,mao

    ------------------------------------------------------
    diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
    index 2a50e0f..12cac5e 100644
    --- a/arch/x86/mm/pat.c
    +++ b/arch/x86/mm/pat.c
    @@ -305,27 +305,6 @@ int reserve_memtype(u64 start, u64 end, unsigned
    long req_type,
    struct memtype, nd);
    }
    break;
    - } else if (start < entry->end) { /* start > entry->start */
    - err = chk_conflict(new, entry, new_type);
    - if (!err) {
    - dprintk("Overlap at 0x%Lx-0x%Lx\n",
    - entry->start, entry->end);
    - cached_entry = list_entry(entry->nd.prev,
    - struct memtype, nd);
    -
    - /*
    - * Move to right position in the linked
    - * list to add this new entry
    - */
    - list_for_each_entry_continue(entry,
    - &memtype_list, nd) {
    - if (start <= entry->start) {
    - where = entry->nd.prev;
    - break;
    - }
    - }
    - }
    - break;
    }
    }
    --
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  2. RE: [patch 0/1]pat: remove redundant condition check



    >-----Original Message-----
    >From: linux-kernel-owner@vger.kernel.org
    >[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of bibo mao
    >Sent: Sunday, October 12, 2008 6:45 AM
    >To: akpm@linux-foundation.org
    >Cc: linux-kernel@vger.kernel.org
    >Subject: [patch 0/1]pat: remove redundant condition check
    >
    >On file pat.c, if (start <= entry->start), it also means (start <
    >entry->end). This patch removes
    >redundant condition check.
    >


    No No.

    start <= entry->start does mean start < entry->end
    but
    start <= entry->end does NOT mean start < entry->start

    This 'else if' is to catch the cases where start < entry->end
    and start > entry->start. Removing it will break the whole
    logic of this function.

    Thanks,
    Venki

    >Signed-off-by: bibo.mao@gmail.com
    >thanks
    >bibo,mao
    >
    >------------------------------------------------------
    >diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
    >index 2a50e0f..12cac5e 100644
    >--- a/arch/x86/mm/pat.c
    >+++ b/arch/x86/mm/pat.c
    >@@ -305,27 +305,6 @@ int reserve_memtype(u64 start, u64 end, unsigned
    >long req_type,
    > struct
    >memtype, nd);
    > }
    > break;
    >- } else if (start < entry->end) { /* start >
    >entry->start */
    >- err = chk_conflict(new, entry, new_type);
    >- if (!err) {
    >- dprintk("Overlap at 0x%Lx-0x%Lx\n",
    >- entry->start, entry->end);
    >- cached_entry =
    >list_entry(entry->nd.prev,
    >- struct
    >memtype, nd);
    >-
    >- /*
    >- * Move to right position in the linked
    >- * list to add this new entry
    >- */
    >- list_for_each_entry_continue(entry,
    >-
    >&memtype_list, nd) {
    >- if (start <= entry->start) {
    >- where = entry->nd.prev;
    >- break;
    >- }
    >- }
    >- }
    >- break;
    > }
    > }
    >--
    >To unsubscribe from this list: send the line "unsubscribe
    >linux-kernel" in
    >the body of a message to majordomo@vger.kernel.org
    >More majordomo info at http://vger.kernel.org/majordomo-info.html
    >Please read the FAQ at http://www.tux.org/lkml/
    >

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