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Date: Sun, 15 Feb 2015 16:06:18 -0800 From: Joe Perches <joe@...ches.com> To: Markus Pargmann <mpa@...gutronix.de> Cc: nbd-general@...ts.sourceforge.net, linux-kernel@...r.kernel.org Subject: Re: [PATCH 6/9] nbd: Restructure debugging prints On Sun, 2015-02-15 at 23:20 +0100, Markus Pargmann wrote: > On Fri, Feb 13, 2015 at 03:48:06AM -0800, Joe Perches wrote: > > On Fri, 2015-02-13 at 12:24 +0100, Markus Pargmann wrote: > > > On Fri, Feb 13, 2015 at 02:05:27AM -0800, Joe Perches wrote: > > > > On Fri, 2015-02-13 at 10:58 +0100, Markus Pargmann wrote: > > > > > On Thu, Feb 12, 2015 at 01:08:48PM -0800, Joe Perches wrote: > > > > > > On Thu, 2015-02-12 at 21:57 +0100, Markus Pargmann wrote: > > > > > > > dprintk has some name collisions with other frameworks and drivers. It > > > > > > > is also not necessary to have these custom debug print filters. Dynamic > > > > > > > debug offers the same amount of filtered debugging. > > > > > > > > > > > > > > This patch replaces all dprintks with dev_dbg(). It also removes the > > > > > > > ioctl dprintk which prints the ingoing ioctls which should be > > > > > > > replaceable by strace or similar stuff. > > > > > > > > > > > > Perhaps add > > > > > > > > > > > > #define nbd_dbg(nbd, fmt, ...) \ > > > > > > dev_dbg(disk_to_dev((nbd)->disk), "%s: " fmt, \ > > > > > > nbd->disk->disk_name, ##__VA_ARGS__) > > > > > > > > > > I am not really happy with those custom debug print macros. What do you > > > > > think about an inline function 'nbd_to_dev' instead? > > > > > > > > Wouldn't that change the output? > > > > What would the output look like? > > > > > > I meant a function that just translates struct nbd_device* to struct > > > device*. That wouldn't change the output. > > > > > > > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c > > > > > > [] > > > > > > > +static void nbd_end_request(struct nbd_device *nbd, struct request *req) > > > > > > > { > > > > > > > int error = req->errors ? -EIO : 0; > > > > > > > struct request_queue *q = req->q; > > > > > > > unsigned long flags; > > > > > > > > > > > > > > - dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name, > > > > > > > - req, error ? "failed" : "done"); > > > > > > > + dev_dbg(disk_to_dev(nbd->disk), "%s: request %p: %s\n", > > > > > > > + req->rq_disk->disk_name, req, error ? "failed" : "done"); > > > > > > > > > > > > so this becomes > > > > > > > > > > > > nbd_dbg(nbd, "request %p: %s\n", > > > > > > req, error ? "failed" : "done"); > > > > > > > > > > so this would be: > > > > > nbd_dbg(nbd_to_dev(nbd), "request %p: %s\n", > > > > > req, error ? "failed" : "done"); > > > > > > > > I don't see much value in that style, > > > > but I don't manage the code either. > > > > > > Oh sorry, I meant to write: > > > dev_dbg(nbd_to_dev(nbd), "request %p: %s\n", > > > req, error ? "failed" : "done"); > > > > > > So the normal dev_dbg call is still there and the expression to get the > > > device from a nbd_device struct is shorter. > > > > Is nbd->disk->disk_name the same string as > > disk_to_dev((nbd)->disk)->name? > > > > What's the output of the conversion in this patch? > > Oh yes, thanks, that's twice the device name then. Will fix that. > > > > > - dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name, > > - req, error ? "failed" : "done"); > > + dev_dbg(disk_to_dev(nbd->disk), "%s: request %p: %s\n", > > + req->rq_disk->disk_name, req, error ? "failed" : "done"); > > > > Should this conversion be as you wrote above > > > > dev_dbg(nbd_to_dev(nbd), "request %p: %s\n", > > req, error ? "failed" : "done"); > > > > If so, then there's probably not much use in a > > custom nbd_dbg macro. > > > > There is some value though in classifying blocks of > > debugging output akin to the use of netif_msg_<type>. > > > > That is lost with these conversions. > > It is still possible to enable/disable particular dev_dbg calls using > the dynamic debug interface. Yes, true, but not by type, only all/none/specific. I've previously proposed mechanisms to categorize dynamic debugging output by type. -- 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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