Messages in this thread | | | Subject | Re: [PATCH] powercap: Adjust printing the constraint name with new line | From | Lukasz Luba <> | Date | Tue, 17 Nov 2020 09:22:02 +0000 |
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Hi Rafael,
On 11/10/20 7:19 PM, Rafael J. Wysocki wrote: > On Mon, Nov 9, 2020 at 6:25 PM Lukasz Luba <lukasz.luba@arm.com> wrote: >> >> The constraint name has limit of size 30, which sometimes might be hit. >> When this happens the new line might be lost. Prevent this and set the >> new line when the name string is too long." >> >> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com> >> --- >> drivers/powercap/powercap_sys.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/drivers/powercap/powercap_sys.c b/drivers/powercap/powercap_sys.c >> index f808c5fa9838..575f9fdb810e 100644 >> --- a/drivers/powercap/powercap_sys.c >> +++ b/drivers/powercap/powercap_sys.c >> @@ -174,6 +174,10 @@ static ssize_t show_constraint_name(struct device *dev, >> "%s\n", name); >> buf[POWERCAP_CONSTRAINT_NAME_LEN] = '\0'; >> len = strlen(buf); >> + >> + /* When the 'name' is too long, don't lose new line */ >> + if (strlen(name) >= POWERCAP_CONSTRAINT_NAME_LEN) >> + buf[POWERCAP_CONSTRAINT_NAME_LEN - 1] = '\n'; > > Wouldn't it be better to pass POWERCAP_CONSTRAINT_NAME_LEN - 1 to > snprintf() above?
My apologies for delay, I was on holidays.
The snprintf() overwrites the '\n' in that case also. I've experimented with it a bit more and tried to come with a bit 'cleaner' solution.
What we are looking is probably: "%.*s\n" semantic. Another solution would be: ------------------------------8<--------------------------- if (name) { - snprintf(buf, POWERCAP_CONSTRAINT_NAME_LEN, - "%s\n", name); - buf[POWERCAP_CONSTRAINT_NAME_LEN] = '\0'; + sprintf(buf, "%.*s\n", POWERCAP_CONSTRAINT_NAME_LEN -1, + name); len = strlen(buf); }
----------------------------->8----------------------------
I've check this and it behaves very well.
It looks cleaner and it is a used pattern in the kernel. What do you think? Is it good for v2?
Regards, Lukasz
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