From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Sverdlin Subject: Re: [PATCH 5/6] OF: Utility helper functions for dynamic nodes Date: Tue, 24 Jun 2014 10:12:52 +0200 Message-ID: <53A93304.9000604@nsn.com> References: <1403430039-15085-1-git-send-email-pantelis.antoniou@konsulko.com> <1403430039-15085-6-git-send-email-pantelis.antoniou@konsulko.com> <53A85549.7040809@nsn.com> <6E91A461-4361-4A18-BE32-CECDD789C114@konsulko.com> <20140623183343.GA10389@heimdall> <78ACBAF6-A73E-4272-8D3A-258C4B10858C@konsulko.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <78ACBAF6-A73E-4272-8D3A-258C4B10858C-OWPKS81ov/FWk0Htik3J/w@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: ext Pantelis Antoniou , Ioan Nicu Cc: Grant Likely , Rob Herring , Stephen Warren , Matt Porter , Koen Kooi , Greg Kroah-Hartman , Alison Chaiken , Dinh Nguyen , Jan Lubbe , Michael Stickel , Guenter Roeck , Dirk Behme , Alan Tull , Sascha Hauer , Michael Bohan , Michal Simek , Matt Ranostay , Joel Becker , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Wolfram Sang , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Mark Brown , linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Pete Popov List-Id: devicetree@vger.kernel.org Hi! On 23/06/14 21:13, ext Pantelis Antoniou wrote: [...] >>> I don't know of any place in the kernel accessing the value if prop->length==0 >>> >> >> We have a simple use case. We have an overlay which adds an interrupt controller. >> If you look in drivers/of/irq.c, in of_irq_parse_raw(): >> >> [...] >> /* Now start the actual "proper" walk of the interrupt tree */ >> while (ipar != NULL) { >> /* Now check if cursor is an interrupt-controller and if it is >> * then we are done >> */ >> if (of_get_property(ipar, "interrupt-controller", NULL) != >> NULL) { >> pr_debug(" -> got it !\n"); >> return 0; >> } >> [...] >> >> A node is identified as an interrupt controller if it has a zero-length property >> called "interrupt-controller" but with a non-NULL value. >> >> My proposed fix for this was to remove the if () condition. propn->value will be >> allocated with kmalloc(0) which returns ZERO_SIZE_PTR which is != NULL. >> > > If that's the case, the code in irq.c is wrong. > > interrupt-controller is a bool property; the correct call to use is of_property_read_bool() > which returns true or false when the value is defined. No, it's not bool... It's an existence of a void property. > The use of of_get_property is a bug here. It is perfectly valid for a property to have a > NULL value when length = 0. of_find_property() would be really correct in this particular case... -- Best regards, Alexander Sverdlin. -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html