linux-kernel - Re: [PATCH] usb: gadget: ffs: add eventfd notification about ffs events

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Message-id: <54C23FE5.9030403@samsung.com>
Date:	Fri, 23 Jan 2015 13:34:45 +0100
From:	Robert Baldyga <r.baldyga@...sung.com>
To:	Michał Nazarewicz <mina86@...a86.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Krzysztof Opasiak <k.opasiak@...sung.com>, balbi@...com,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH] usb: gadget: ffs: add eventfd notification about ffs events

On 01/23/2015 01:21 PM, Michał Nazarewicz wrote:
> 23 sty 2015 10:28 "Robert Baldyga" <r.baldyga@...sung.com
> <mailto:r.baldyga@...sung.com>> napisał(a):
>> Add eventfd which notifies userspace about ep0 events and AIO completion
>> events. It simplifies using of FunctionFS with event loop, because now
>> we need to poll on single file (instead of polling on ep0 and eventfd's
>> supplied to AIO layer).
>>
>> FunctionFS eventfd is not triggered if another eventfd is supplied to
>> AIO layer (in AIO request). It can be useful, for example, when we want
>> to handle AIO transations for chosen endpoint in separate thread.
>>
>> Signed-off-by: Robert Baldyga
> 
> I don't know much about eventfd interface bit from ffs point of view:
> 
> Acked-by: Michal Nazarewicz <mina86@...a86.com <mailto:mina86@...a86.com>>
> 
>> @@ -2180,6 +2191,20 @@ static int __ffs_data_got_descs(struct ffs_data
> *ffs,
>>                 goto error;
>>         }
>>
>> +       if (flags & FUNCTIONFS_EVENTFD) {
>> +               if (len < 4)
>> +                       goto error;
>> +               ffs->ffs_eventfd =
>> +                       eventfd_ctx_fdget((int)get_unaligned_le32(data));
>> +               if (IS_ERR(ffs->ffs_eventfd)) {
>> +                       ffs->ffs_eventfd = NULL;
>> +                       ret = PTR_ERR(ffs->ffs_eventfd);
> 
> Need to swap those lines.
> 
>> +                       goto error;
>> +               }
>> +               data += 4;
>> +               len  -= 4;
>> +       }
>> +
>>         /* Read fs_count, hs_count and ss_count (if present) */
>>         for (i = 0; i < 3; ++i) {
>>                 if (!(flags & (1 << i))) {
> 

Good catch, thanks!

Best regards,
Robert Baldyga
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