lkml.org 
[lkml]   [2016]   [Mar]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] mtd: nand: check status before reporting timeout
Date
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
\
 
 \ /
  Last update: 2016-03-05 03:01    [W:0.145 / U:0.148 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site