From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1C5F08F77 for ; Sat, 4 Jan 2025 00:19:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735949994; cv=none; b=BDYYXG1BcB0Pte2KaVeENSpCk0EDGo1qVTgcFYt0sqkE3VpEAXsp2c2qfEcHN4xKzoUvsfnhQbjxBZEFEoFKVch6FjR2ZNeBb2JeSb8aD6K516NzNSNWYNQcsqx1rIlg8vJU81GTCxqFAErjTsl2ZFieRD0tBiW7rGrd8bCXsqY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735949994; c=relaxed/simple; bh=46KEX8fD9h8wCCqLKZNWkPZ6VL+RAR67wWbL9J5fFL8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tQi6jJTPAvcvnhxhqFKl6FPBjoFkZ9ZqaPkPn/ceFXCYCmFpt17hDkvLxu5fVKwjEskAlrtLCuq/JUfyhVWoLZTZFWxcPTxYC5+4Ji0URmG1QSlgF34StNAJ3mLyZisREPffVRnewe7XAoIdTIYXHv2TH26JCwcAhZPxL96UEK8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oFk4cr2g; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="oFk4cr2g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 81239C4CEDD; Sat, 4 Jan 2025 00:19:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1735949993; bh=46KEX8fD9h8wCCqLKZNWkPZ6VL+RAR67wWbL9J5fFL8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=oFk4cr2g63paLl349HZ6QZRX0QUW/X4PzrFOT0ZV4zIa++6llanD9DMIjQPQ6Hh0T sCmJyiTDym6dYIfglyckSixzcnGYgiOP9hhoNT0bO6jDYwY5rbHXzX6iwxj7z+Vg9b EXcg1Drd/Q7qeqBiixggrFxfpZdaQ3ktuGo7cZ+DPbxIB9KDbC4P6NH5WaoeM47hTz NLUxoqxIhwJ38vnw9BSIWmKSUpEV4sm2C33DY4MHrlRtT4PRAixGPsGYdjCGDW/9tR KBeRDfa+GeGyHjGhK+Hs3xIzCHEttw1iOrAbiOaIQpIUDwm1Ep2ZvimJdjEeZ3TK8t OMa1scujdvZTA== Date: Sat, 4 Jan 2025 01:19:48 +0100 From: Niklas Cassel To: Bjorn Helgaas Cc: Jingoo Han , Manivannan Sadhasivam , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Rob Herring , Bjorn Helgaas , Damien Le Moal , linux-pci@vger.kernel.org Subject: Re: [PATCH v2] PCI: dwc: Fix W=1 build warning in dw_pcie_edma_irq_verify() Message-ID: References: <20250102111339.2233101-2-cassel@kernel.org> <20250103221056.GA9766@bhelgaas> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250103221056.GA9766@bhelgaas> On Fri, Jan 03, 2025 at 04:10:56PM -0600, Bjorn Helgaas wrote: > Can you make the subject say something about the fix instead of the > warning? E.g., something about fixing a potential truncation? > > On Thu, Jan 02, 2025 at 12:13:40PM +0100, Niklas Cassel wrote: > > Change dw_pcie_edma_irq_verify() to print the dma channel as %u. > > > > While a DWC glue driver could theoretically initialize nr_irqs to a > > negative value, doing so would obviously be incorrect, and the later > > dw_edma_probe(struct dw_edma_chip *chip) call would fail, since while > > the dw_edma_probe() call expects the caller to initialize chip->nr_irqs, > > dw_edma_probe() verifies nr_irqs and returns failure if nr_irqs is < 1. > > > > This fixes the following build warning when compiling with W=1: > > > > drivers/pci/controller/dwc/pcie-designware.c: In function ‘dw_pcie_edma_detect’: > > drivers/pci/controller/dwc/pcie-designware.c:989:50: warning: ‘%d’ directive output may be truncated writing between 1 and 11 bytes into a region of size 3 [-Wformat-truncation=] > > 989 | snprintf(name, sizeof(name), "dma%d", pci->edma.nr_irqs); > > | ^~ > > > > Signed-off-by: Niklas Cassel > > --- > > Changes since V1: > > -Do not reject negative nr_irqs value in dw_pcie_edma_irq_verify(), > > as this will already be done by dw_edma_probe(). > > > > drivers/pci/controller/dwc/pcie-designware.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c > > index 3c683b6119c3..0a13fb4336f4 100644 > > --- a/drivers/pci/controller/dwc/pcie-designware.c > > +++ b/drivers/pci/controller/dwc/pcie-designware.c > > @@ -986,7 +986,7 @@ static int dw_pcie_edma_irq_verify(struct dw_pcie *pci) > > } > > > > for (; pci->edma.nr_irqs < ch_cnt; pci->edma.nr_irqs++) { > > - snprintf(name, sizeof(name), "dma%d", pci->edma.nr_irqs); > > + snprintf(name, sizeof(name), "dma%u", pci->edma.nr_irqs); > > I don't understand this fix. I guess the warning is complaining that > sizeof(name) == 6, and "dma" takes up three bytes, so the %d has to > fit in the remaining region of size 3? Yes. > > But I don't see how printing nr_irqs as unsigned rather than signed is > a fix, since even an unsigned int can be longer than 3 digits. You would need to ask GCC authors behind -Wformat-truncation why the warning only seems to care about %d. > > And I don't like using "%u" for a signed value in order to "fix" > something. That's asking for a future cleanup to revert the change. > Well, neither do I. V1 was a nicer solution IMO: https://lore.kernel.org/linux-pci/20241220072328.351329-2-cassel@kernel.org/ But that fix was rejected by another PCI maintainer. > What's wrong with just making the name[] buffer big enough? Sure, I'll do that in v3. Kind regards, Niklas