USB: mon: no need to check return value of debugfs_create functions
PATCH 5/22 USB: mon: no need to check return value of debugfs_create functions
Hi Greg,
Quoted 8 lines · Greg Kroah-Hartman
Quoted 7 lines · Pete Zaitcev
Quoted 3 lines · On Tue, 29 May 2018 17:30:50 +0200 Greg Kroah-Hartman…
When calling debugfs functions, there is no need to ever check the return value. The function can work or not, but the code logic should never do something different based on this.
Quoted 7 lines
Quoted 4 lines
Okay, fair enough. And the code works, surprisingly, even when the debugfs is disabled (well, according to my review). I just have one question - wouldn't it be cleaner to deprecate and remove the text API altogether?
If you think we can do that, sure! But what's the odds that someone still uses it? This patch doesn't change any real functionality.
I had some use of this text API last year, when I also discovered and submitted and fix for its data corruption problems described in commit a5f596830e27e "usb: usbmon: Read text within supplied buffer size".
A significant disadvantage with the text API is, as far as I understand it, that it can drop events (due to its buffering limit) without informing API readers (via event sequence numbers or some such).
I've found a couple of USB bugs/problems (commit d6c931ea32dc0 "USB: OHCI:
Fix NULL dereference in HCDs using HCD_LOCAL_MEM" for instance) and I'm still investigating at least one bug possibly related to lost interrupts where some kind of probing method could be helpful.
However, I would explore other kernel probing methods for that. Not only because I'm curious but also because I have the impression that there are more powerful methods available than this text API. Would you recommend any alternatives?
Fredrik
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