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On Wed, Mar 08, 2006 at 01:06:59AM -0500, Dmitry Torokhov wrote: > On Wednesday 08 March 2006 00:23, Greg KH wrote:> > > > > > Hmm, what is the policy for attr->show()? With hotplug variables we > > > return -ENOMEM if there is not enough memory to store all data, but > > > what about attributes? Should we also return error (and which one, > > > -ENOMEM, -ENOBUFS?) or fill as much as we can and return up to > > > PAGE_SIZE?> > > > Remember, sysfs files are supposed to be small, you are an "oddity" in > > that you have a much larger buffer that you can return due to the wierd > > aliases you have. > > > > Truncating the buffer is probably good as we want userspace to get some > > information, right? > > > > > With sysfs not kernel nor application can really recover > > > if attribute needs buffer larger than a page. Or just rely on BUG_ON > > > in fs/sysfs/file.c::fill_read_buffer()? > > > > How about just making this a binary attribute, then you can handle an > > arbitrary size buffer and don't have to worry about the PAGE_SIZE stuff > > (but it makes it more code that you have to write to handle it all, > > there are tradeoffs...) > > > > I really don't believe that we ever going to cross 4096 boundary for any > single input attribute, but just to code defensively we need to decide > what to do if we ever encounter a crazy device. Just truncating to > PAGE_SIZE is easiest so that's what I am going to do. Ok, that's fine with me. thanks, greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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