Messages in this thread | | | Subject | Re: [PATCH] Revert "staging:r8188eu: use lib80211 CCMP decrypt" | From | Michael Straube <> | Date | Tue, 1 Jan 2019 20:31:31 +0100 |
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On 1/1/19 3:17 AM, Larry Finger wrote: > On 12/30/18 12:39 PM, Michael Straube wrote: >> Commit 6bd082af7e36 ("staging:r8188eu: use lib80211 CCMP decrypt") >> is causing hardfreeze whenever the driver tries to connect to my wifi >> network. That makes the driver unusable on my system. Reverting the >> commit fixes the issue and the driver works properly. >> >> Dec 29 19:21:17 gentoo kernel: BUG: scheduling while atomic: swapper/6/0/0x00000100 > > Michael, > > I have verified the freezes that you see. Although I have not been able to capture the console dump, I think we are likely seeing the same problem. > > I do have a work-around in that I have not gotten any freezes when I force module lib80211_crypt_ccmp to be loaded before I load module r8188eu. This clue was used in finding what seems to be a good fix. > > I do not know anything about demand loading of modules using try_then_request_module(); however, I noticed that the macro actually calls __request_module(), which has the following comment: > > * Load a module using the user mode module loader. The function returns > * zero on success or a negative errno code or positive exit code from > * "modprobe" on failure. Note that a successful module load does not mean > * the module did not then unload and exit on an error of its own. Callers > * must check that the service they requested is now available not blindly > * invoke it. > > I note that it says "user mode module loader". Routine rtw_aes_decrypt() is likely inside some sort of locking, which leads to the "scheduling while atomic" bug that you see. As a result, I suspect that the module is not loaded, and that leads to the NULL dereference when the module is accessed. Please try the one-line patch attached, which forces lib80211 to load when r8188eu is loaded. With this patch, I have been connected to an AES-encrypted AP for nearly 3 hours with no problems. > > Larry > >
I've tested your patch and it solved the issue. No freezes and dmesg looks good.
I noticed that try_then_request_module() is also used in rtw_wep_encrypt() and rtw_wep_decrypt(). I guess that also could cause problems?
Michael
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