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McKenney" , Mahesh J Salgaonkar , Oliver O'Halloran , Kai-Heng Feng , Keith Busch , Robert Richter , Terry Bowman , Shiju Jose , Dave Jiang , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Bjorn Helgaas , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= Subject: Re: [PATCH v7 01/17] PCI/DPC: Initialize aer_err_info before using it Message-ID: <20250521191803.GA1426656@bhelgaas> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250521095218.0000045d@huawei.com> On Wed, May 21, 2025 at 09:52:18AM +0100, Jonathan Cameron wrote: > On Tue, 20 May 2025 16:50:18 -0500 > Bjorn Helgaas wrote: > > > From: Bjorn Helgaas > > > > Previously the struct aer_err_info "info" was allocated on the stack > > without being initialized, so it contained junk except for the fields we > > explicitly set later. > > > > Initialize "info" at declaration so it starts as all zeros. > > > > Signed-off-by: Bjorn Helgaas > > Tested-by: Krzysztof Wilczyński > > Reviewed-by: Kuppuswamy Sathyanarayanan > > I chased this through a bit and looks like at least some unset fields would > result in garbage prints. So maybe needs a fixes tag? > info->tlp_header_valid is an easy one to follow as only set in some paths. I don't see a current issue related to info->tlp_header_valid because it's always cleared in the path from DPC: dpc_process_error dpc_get_aer_uncorrect_severity info->severity = AER_FATAL or AER_NONFATAL aer_get_device_error_info info->status = 0; info->tlp_header_valid = 0; # unconditional pci_read_config_dword(PCI_ERR_UNCOR_STATUS, &info->status); pci_read_config_dword(PCI_ERR_UNCOR_MASK, &info->mask); info->first_error = PCI_ERR_CAP_FEP(...); aer_print_error However, only info->{severity,status,tlp_header_valid,mask, first_error} are initialized before dpc_process_error() calls aer_print_error(), and aer_print_error() uses info->{id, error_dev_num}, which haven't been initialized. AFAICT, this has been the case since https://git.kernel.org/linus/8aefa9b0d910 ("PCI/DPC: Print AER status in DPC event handling") Here's aer_get_device_error_info() at that time: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/pcie/aer.c?id=8aefa9b0d910#n867 and aer_print_error(): https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/pcie/aer.c?id=8aefa9b0d910#n530 At the time of 8aefa9b0d910, info->severity was also used without initialization; this was fixed by 9f08a5d896ce ("PCI/DPC: Fix print AER status in DPC event handling"). But I think the info->{id,error_dev_num} has been there since. Anyway, I added: Fixes: 8aefa9b0d910 ("PCI/DPC: Print AER status in DPC event handling") > Otherwise absolutely makes sense. > Reviewed-by: Jonathan Cameron > > --- > > drivers/pci/pcie/dpc.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c > > index df42f15c9829..3daaf61c79c9 100644 > > --- a/drivers/pci/pcie/dpc.c > > +++ b/drivers/pci/pcie/dpc.c > > @@ -258,7 +258,7 @@ static int dpc_get_aer_uncorrect_severity(struct pci_dev *dev, > > void dpc_process_error(struct pci_dev *pdev) > > { > > u16 cap = pdev->dpc_cap, status, source, reason, ext_reason; > > - struct aer_err_info info; > > + struct aer_err_info info = {}; > > > > pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status); > > pci_read_config_word(pdev, cap + PCI_EXP_DPC_SOURCE_ID, &source); >