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From: Greg KH <gregkh@linuxfoundation.org>
To: antoniprzybylik <antoni.przybylik@wp.pl>
Cc: devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] staging: gdm724x: gdm_tty: corrected macro by adding brackets
Date: Tue, 1 Sep 2020 13:08:38 +0200	[thread overview]
Message-ID: <20200901110838.GA273488@kroah.com> (raw)
In-Reply-To: <20200901104311.17270-1-antoni.przybylik@wp.pl>

On Tue, Sep 01, 2020 at 12:43:11PM +0200, antoniprzybylik wrote:
> Such macros are dangerous. Consider following example:
> 	#define GDM_TTY_READY(gdm) (gdm && gdm->tty_dev && gdm->port.count)
> 	GDM_TTY_READY(a + b)
> This macro will be expanded in such a way:
> 	(a + b && a + b->tty_dev && a + b->port.count)
> And it will lead to errors.

This is for a pointer, no one would ever do that :)

But, if you really worry about this, turn it into an inline function,
that way you get the proper typedef safety, which is what something like
this should really be, not a macro.

thanks,

greg k-h

  reply	other threads:[~2020-09-01 11:31 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-01 10:43 antoniprzybylik
2020-09-01 11:08 ` Greg KH [this message]
2020-09-01 13:33 ` Dan Carpenter

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