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    SubjectRE: [PATCH v3] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer
    Date


    > -----Original Message-----
    > From: linux-mtd [mailto:linux-mtd-bounces@lists.infradead.org] On Behalf
    > Of Liu Jian
    > Sent: Tuesday, February 26, 2019 11:01 PM
    > To: dwmw2@infradead.org; computersforpeace@gmail.com;
    > bbrezillon@kernel.org; marek.vasut@gmail.com; richard@nod.at;
    > joakim.tjernlund@infinera.com; ikegami@allied-telesis.co.jp;
    > keescook@chromium.org; vigneshr@ti.com
    > Cc: linux-mtd@lists.infradead.org; liujian56@huawei.com;
    > linux-kernel@vger.kernel.org
    > Subject: [PATCH v3] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer
    >
    > In function do_write_buffer(), in the for loop, there is a case
    > chip_ready() returns 1 while chip_good() returns 0, so it never
    > break the loop.
    > To fix this, chip_good() is enough and it should timeout if it stay
    > bad for a while.
    >
    > Fixes: dfeae1073583("mtd: cfi_cmdset_0002: Change write buffer to check
    > correct value")
    > Signed-off-by: Yi Huaijie <yihuaijie@huawei.com>
    > Signed-off-by: Liu Jian <liujian56@huawei.com>
    > Reviewed-by: Tokunori Ikegami <ikegami_to@yahoo.co.jp>
    > ---
    > v2->v3:
    > Follow Vignesh's advice:
    > add one more check for check_good() even when time_after() returns true.
    >
    > drivers/mtd/chips/cfi_cmdset_0002.c | 2 +-
    > 1 file changed, 1 insertion(+), 1 deletion(-)
    >
    > diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c
    > b/drivers/mtd/chips/cfi_cmdset_0002.c
    > index 72428b6..3da2376 100644
    > --- a/drivers/mtd/chips/cfi_cmdset_0002.c
    > +++ b/drivers/mtd/chips/cfi_cmdset_0002.c
    > @@ -1876,7 +1876,7 @@ static int __xipram do_write_buffer(struct map_info
    > *map, struct flchip *chip,
    > continue;
    > }
    >
    > - if (time_after(jiffies, timeo) && !chip_ready(map, adr))
    > + if (time_after(jiffies, timeo) && !chip_good(map, adr,
    > datum))

    Just another idea to understand easily.

    unsigned long now = jiffies;

    if (chip_good(map, adr, datum)) {
    xip_enable(map, chip, adr);
    goto op_done;
    }

    if (time_after(now, timeo) {
    break;
    }

    Regards,
    Ikegami

    > break;
    >
    > if (chip_good(map, adr, datum)) {
    > --
    > 2.7.4
    >
    >
    > ______________________________________________________
    > Linux MTD discussion mailing list
    > http://lists.infradead.org/mailman/listinfo/linux-mtd/

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