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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>, linux-parisc@vger.kernel.org
Subject: Re: [PATCH v1] parisc: Use for_each_console() helper
Date: Fri, 24 Jan 2020 19:38:46 +0200	[thread overview]
Message-ID: <20200124173846.GL32742@smile.fi.intel.com> (raw)
In-Reply-To: <1579883942.3001.14.camel@HansenPartnership.com>

On Fri, Jan 24, 2020 at 08:39:02AM -0800, James Bottomley wrote:
> On Fri, 2020-01-24 at 18:07 +0200, Andy Shevchenko wrote:
> > Replace open coded single-linked list iteration loop with
> > for_each_console()
> > helper in use.

> > -	while ((console = console_drivers) != NULL)
> > -		unregister_console(console_drivers);
> > +	for_each_console(console)
> > +		unregister_console(console);
> 
> This is wrong.  The old formulation iterates correctly in the face of
> element removal.  for_each_console is defined:
> 
> #define for_each_console(con) \
> 	for (con = console_drivers; con != NULL; con = con->next)
> 
> So it's not safe for any iteration that alters the list elements.

Ah, I see. In this case we need to keep a pointer to the next element.
Though, the original code assumes that console_drivers after unregistration
will be promoted to the next element. Do we have this assumption solid?

Thanks!

-- 
With Best Regards,
Andy Shevchenko



  reply	other threads:[~2020-01-24 17:38 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-24 16:07 [PATCH v1] parisc: Use for_each_console() helper Andy Shevchenko
2020-01-24 16:39 ` James Bottomley
2020-01-24 17:38   ` Andy Shevchenko [this message]
2020-01-24 17:59     ` James Bottomley
2020-01-25 10:25       ` Andy Shevchenko
2020-01-27  8:48         ` Helge Deller
2020-01-27  9:47           ` Andy Shevchenko
2020-01-30 14:07             ` Petr Mladek

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