Re: [PATCH] usb: gadget: ffs: don't allow to open with O_NONBLOCK flag

From: Michal Nazarewicz
Date: Tue Apr 07 2015 - 15:48:39 EST

> From: Robert Baldyga
>> I want rather to inform users that non-blocking i/o wouldn't work for
>> epfiles. Indeed we can handle O_NONBLOCK for ep0 (for the same reason we
>> can have poll), but for other epfiles there is no way to check if
>> read/write operation can end up in short time. Everything is up to host.

On Tue, Apr 07 2015, David Laight wrote:
> Is that really necessary?
> I'm sure there are a lot of device drivers that ignore O_NONBLOCK.

FFS partially supports O_NONBLOCK which may fool people into thinking it
has full support.

epfiles donât implement poll though so Iâm not sure how users would
imagine O_NONBLOCK being used with them. ep0, on the other hand,
implements poll and (as far as I can see and despite what Robert wrote)
suffers from the same problem so it may be considered a bigger issue.

Overall though, I do agree that we need to consider whether the current
situation is really a serious problem.

Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, MichaÅ âmina86â Nazarewicz (o o)
ooo +--<mpn@xxxxxxxxxx>--<xmpp:mina86@xxxxxxxxxx>--ooO--(_)--Ooo--
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