Re: [PATCH net] netdevsim: avoid NULL dereference after failed probe

[Jakub Kicinski <kuba@kernel.org>]

On Thu, 15 Oct 2026 10:01:33 +0200 Daniel Machon wrote:
> There might be another approach though. Did you explore nsim_driver.dev_groups?
> Adding nsim_bus_dev_new_port_attr/nsim_bus_dev_del_port_attr there might work,
> and the fix will be simpler. I cant claim to be an expert in this area, but it
> might be wort investigating.

I had a similar feeling, but looks like nsim_bus_dev_numvfs_store()
already checks drvdata :\ Let's stick to this approach, but please
fix the flow to look identical to the check in numvfs_store:

        device_lock(dev);                                                       
        ret = -ENOENT;                                                          
        if (dev_get_drvdata(dev))                                               
                ret = nsim_XXX(nsim_bus_dev, num_vfs);            
        device_unlock(dev);     

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- How the issue was discovered, e.g. hit in production, hit during
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  analysis tool scan.

 - Whether the issue was actually triggered, or is only theoretical
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   the symptoms, like the stack trace or error messages.
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