Messages in this thread Patch in this message | | | From | Brian Norris <> | Subject | [PATCH] mtd: nand: check status before reporting timeout | Date | Fri, 4 Mar 2016 17:19:23 -0800 |
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In commit b70af9bef49b ("mtd: nand: increase ready wait timeout and report timeouts"), we increased the likelihood of scheduling during nand_wait(). This makes us more likely to hit the time_before(...) condition, since a lot of time may pass before we get scheduled again.
Now, the loop was already buggy, since we don't check if the NAND is ready after exiting the loop; we simply print out a timeout warning. Fix this by doing a final status check before printing a timeout message.
This isn't actually a critical bug, since the only effect is a false warning print. But too many prints never hurt anyone, did they? :)
Side note: perhaps I'm not smart enough, but I'm not sure what the best policy is for this kind of loop; do we busy loop (i.e., no cond_resched()) to keep the lowest I/O latency (it's not great if the resched is delaying Richard's system ~400ms)? Or do we allow rescheduling, to play nice with the rest of the system (since some operations can take quite a while)?
Reported-by: Richard Weinberger <richard@nod.at> Signed-off-by: Brian Norris <computersforpeace@gmail.com> Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com> Reviewed-by: Richard Weinberger <richard@nod.at> Reviewed-by: Harvey Hunt <harvey.hunt@imgtec.com> --- drivers/mtd/nand/nand_base.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index f2c8ff398d6c..596a9b0503da 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -566,8 +566,8 @@ void nand_wait_ready(struct mtd_info *mtd) cond_resched(); } while (time_before(jiffies, timeo)); - pr_warn_ratelimited( - "timeout while waiting for chip to become ready\n"); + if (!chip->dev_ready(mtd)) + pr_warn_ratelimited("timeout while waiting for chip to become ready\n"); out: led_trigger_event(nand_led_trigger, LED_OFF); } -- 2.7.0.rc3.207.g0ac5344
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