Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030963AbbEEItL (ORCPT ); Tue, 5 May 2015 04:49:11 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:50174 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030921AbbEEIst (ORCPT ); Tue, 5 May 2015 04:48:49 -0400 Date: Tue, 5 May 2015 11:48:30 +0300 From: Dan Carpenter To: Jose Rivera Cc: "devel@driverdev.osuosl.org" , "agraf@suse.de" , "arnd@arndb.de" , "bhupesh.sharma@freescale.com" , "gregkh@linuxfoundation.org" , "linux-kernel@vger.kernel.org" , Stuart Yoder , Scott Wood , "nir.erez@freescale.com" , "itai.katz@freescale.com" , "bhamciu1@freescale.com" , "R89243@freescale.com" , Richard Schmitt Subject: Re: [PATCH 1/7] staging: fsl-mc: MC bus IRQ support Message-ID: <20150505084830.GL16501@mwanda> References: <1430242750-17745-1-git-send-email-German.Rivera@freescale.com> <1430242750-17745-2-git-send-email-German.Rivera@freescale.com> <20150430114957.GW14154@mwanda> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2554 Lines: 61 On Mon, May 04, 2015 at 10:09:08PM +0000, Jose Rivera wrote: > > > + WARN_ON((int16_t)irq_count < 0); > > > > This code is doing "WARN_ON(test_bit(15, (unsigned long *)&irq_count));". > > That seems like nonsense. Anyway, just delete the WARN_ON(). > > > I disagree. This WARN_ON is checking that irq_count is in the expected range > (it fits in int16_t as a positive number). The dprc_scan_objects() function > expects irq_count to be of type "unsigned int" (which is 32-bit unsigned) > You're not allowed to disagree because it's a testable thing and not an opinion about style or something. :P What you want is: WARN_ON(irq_count > SHRT_MAX); > > > + > > > + if ((int16_t)irq_count > > > > + mc_bus->resource_pools[FSL_MC_POOL_IRQ].max_count) { > > > > Why are we casting this? Also can you align it like: > > > This casting is done for safety, to prevent the comparison to be done > in "unsigned int" due to integer promotion rules. We are truncating away the top bytes but then we use them later. Fortunately we use them only to print out a warning, but if we used them for anything else it would be a serious bug. Are you expecting .max_count to be negative? If not then both sides are positive and type promotion is fine. We can delete the first (buggy) warning, like I said and just leave the second warning. It will now complain if any of bits 16 to 31 are set where before it wouldn't. > > to read what "goto error;" does. The error handling here calls > > devm_kfree() which is not needed... devm_ functions automatically clean > > up after themselves. This seems a pattern throughout. Do a search for > > devm_free() and see which ones are really needed or not. > > > I know that memory allocated with devm_kzalloc() is freed at the end of the > lifetime of the device it is attached to. However, in error paths, why wait > until the device is destroyed? Why not free the memory earlier so that it > can be used for other purposes? My understanding is that devm_ functions are supposed to be used in the probe() functions to simplify the error handling. So hopefully the device lifetime ends as soon as this function returns a failure. devm_ function are not a use them everywhere because now the kernel has garbage collection type thing. regards, dan carpenter -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/