On Wed, Oct 04, 2023 at 05:59:09AM +0000, Starke, Daniel wrote: > > Daniel, any thoughts? > > Our application of this protocol is only with specific modems to enable > circuit switched operation (handling calls, selecting/querying networks, > etc.) while doing packet switched communication (i.e. IP traffic over PPP). > The protocol was developed for such use cases. > > Regarding the issue itself: > There was already an attempt to fix all this by switching from spinlocks to > mutexes resulting in ~20% performance loss. However, the patch was reverted > as it did not handle the T1 timer leading into sleep during atomic within > gsm_dlci_t1() on every mutex lock there. > There was also a suggestion to fix this in do_con_write() as > tty_operations::write() appears to be documented as "not allowed to sleep". > The patch for this was rejected. It did not fix the issue within n_gsm. > > Link: https://lore.kernel.org/all/20221203215518.8150-1-pchelkin@xxxxxxxxx/ > Link: https://lore.kernel.org/all/20221212023530.2498025-1-zengheng4@xxxxxxxxxx/ > Link: https://lore.kernel.org/all/5a994a13-d1f2-87a8-09e4-a877e65ed166@xxxxxxxxxx/ Ok, I thought I remembered this, I'll just drop this patch from my review queue and wait for a better solution if it ever comes up as this isn't a real issue that people are seeing on actual systems, but just a syzbot report. thanks, greg k-h
