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Date: Mon, 1 Sep 2014 12:59:05 +0200 From: Geert Uytterhoeven <geert@...ux-m68k.org> To: Andy Shevchenko <andy.shevchenko@...il.com> Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Al Viro <viro@...iv.linux.org.uk>, Tadeusz Struk <tadeusz.struk@...el.com>, Herbert Xu <herbert@...dor.apana.org.au>, Mauro Carvalho Chehab <m.chehab@...sung.com>, Helge Deller <deller@....de>, Ingo Tuchscherer <ingo.tuchscherer@...ibm.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Joe Perches <joe@...ches.com>, Marek Vasut <marex@...x.de> Subject: Re: [PATCH v3 1/5] seq_file: provide an analogue of print_hex_dump() Hi Andy, On Mon, Sep 1, 2014 at 12:15 PM, Andy Shevchenko <andy.shevchenko@...il.com> wrote: >>>> I think it needs a call to seq_set_overflow() in case the buffer is too small, >>>> so the caller will retry with a bigger buffer. >>> >>> Yes, in two places it would be useful to do. >> >> Two places? I see only one, just before calling hex_dump_to_buffer. > > seq_putc doesn't set it as I can see. > >>> But what the condition for "buffer is too small", the same groupsize * 2 >>> + 1 or you mean something else? >> >> "groupsize * 2 + 1" is not the amount of bytes hex_dump_to_buffer() wants >> to write. It's only the size for one word. >> >> You could check if there are at least "32 * 3 + 2 + 32 + 1" bytes (your >> old linebuf size) available. > > This is a good question why this number? What if we have to print only > one byte (as different groupsize)? I don't think complaining about a too-small buffer prematurely hurts. > I think the requirement for one groupsize is quite okay. Then you will loose data if the buffer is too small. >> However, to protect against overflows if hex_dump_to_buffer() ever changes, >> I think it would be better to let hex_dump_to_buffer() indicate if the >> passed buffer was to small (it already checks the passed linebuflen). >> Then you can just check for that. > > I thought about that. We may introduce either new call and make > current one the user of it or change all occurrences. > Nevertheless, currently it will print only one groupsize if there is > enough room for it but for two or more. > Thus, I prefer to keep the behaviour "print until we can". The idea of seq_*() is that it will retry with a bigger bufsize if there's not enough space. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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