On Thu, 28 Feb 2019 15:12:15 +0000 "liujian (CE)" <[email protected]> wrote:
> > -----Original Message----- > > From: Tokunori Ikegami [mailto:[email protected]] > > Sent: Thursday, February 28, 2019 10:26 PM > > To: liujian (CE) <[email protected]>; [email protected]; > > [email protected]; [email protected]; > > [email protected]; [email protected]; [email protected]; > > [email protected]; [email protected]; [email protected] > > Cc: [email protected]; [email protected] > > Subject: RE: [PATCH v3] cfi: fix deadloop in cfi_cmdset_0002.c > > do_write_buffer > > > > > > > > > -----Original Message----- > > > From: linux-mtd [mailto:[email protected]] On > > > Behalf Of Liu Jian > > > Sent: Tuesday, February 26, 2019 11:01 PM > > > To: [email protected]; [email protected]; > > > [email protected]; [email protected]; [email protected]; > > > [email protected]; [email protected]; > > > [email protected]; [email protected] > > > Cc: [email protected]; [email protected]; > > > [email protected] > > > 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 <[email protected]> > > > Signed-off-by: Liu Jian <[email protected]> > > > Reviewed-by: Tokunori Ikegami <[email protected]> > > > --- > > > 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; > > } > > > > Thank you~. It is more easier to understand！ > If there are no other comments, I will send new patch again ): Except this version no longer does what Vignesh suggested. See how you no longer test if chip_good() is true if time_after() returns true. So, imagine the thread entering this function is preempted just after the first chip_good() test, and resumed a few ms later. time_after() will return true, but chip_good() might also return true, and you ignore it.
