On 5/25/2021 8:43 AM, Greg Kroah-Hartman wrote:
On Tue, May 25, 2021 at 08:38:34AM +0200, Arend van Spriel wrote:On 5/24/2021 4:48 PM, Sasha Levin wrote:From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> [ Upstream commit 419b4a142a7ece36cebcd434f8ce2af59ef94b85 ] The brcmfmac driver ignores any errors on initialization with the different busses by deferring the initialization to a workqueue and ignoring all possible errors that might happen. Fix up all of this by only allowing the module to load if all bus registering worked properly.Hi Greg, Saw this one flying by for stable kernel. Actually the first time I saw this patch, because I don't follow LKML as much as linux-wireless. The patch is fine, but wanted to give some context on the workqueue approach. It was there for historic reasons. Back then we had the UMH to provide firmware loading and because we request firmware during driver probe we could cause kernel boot to show significant delay when driver was built-in. Hence the workqueue which allowed kernel boot to proceed and driver probe was running in another thread context. These days we have direct firmware loading from the kernel and brcmfmac uses the asynchronous firmware loading API so there is indeed no longer a need for the workqueue. Just for my understanding could you explain the motivation behind this change. In the preceding revert patch I saw this remark: """ The original commit here did nothing to actually help if usb_register() failed, so it gives a "false sense of security" when there is none. The correct solution is to correctly unwind from this error. """ Does this mean the patch is addressing some security issue. Before your patch the module would remain loaded despite a bus register failure. I guess there is a story behind this that I am curious about.The module would remain loaded, yes, but nothing would work, and so no one would have any idea that something went wrong. The original commit was wrong, it did not actually solve anything.
Agree.
This commit properly propagates any error that happens back to the user, like any other module being loaded.
I understand, but this might cause a regression for the user. For instance if the usb_register() fails, but the other driver registrations succeed and the user has a wireless PCIe device. Before this change the user would have a functioning wifi device, but with this change it does not?
Regards, Arend --This electronic communication and the information and any files transmitted with it, or attached to it, are confidential and are intended solely for the use of the individual or entity to whom it is addressed and may contain information that is confidential, legally privileged, protected by privacy laws, or otherwise restricted from disclosure to anyone else. If you are not the intended recipient or the person responsible for delivering the e-mail to the intended recipient, you are hereby notified that any use, copying, distributing, dissemination, forwarding, printing, or copying of this e-mail is strictly prohibited. If you received this e-mail in error, please return the e-mail to the sender, delete it from your computer, and destroy any printed copy of it.
Attachment:
smime.p7s
Description: S/MIME Cryptographic Signature
