On 05/24/2018 02:11 PM, Vladimir Zapolskiy wrote: > For ages trivial changes to RAVB and SuperH ethernet links by means of > standard 'ethtool' trigger a 'sleeping function called from invalid > context' bug, to visualize it on r8a7795 ULCB: > > % ethtool -r eth0 > BUG: sleeping function called from invalid context at kernel/locking/mutex.c:747 > in_atomic(): 1, irqs_disabled(): 128, pid: 554, name: ethtool > INFO: lockdep is turned off. > irq event stamp: 0 > hardirqs last enabled at (0): [<0000000000000000>] (null) > hardirqs last disabled at (0): [<ffff0000080e1d3c>] copy_process.isra.7.part.8+0x2cc/0x1918 > softirqs last enabled at (0): [<ffff0000080e1d3c>] copy_process.isra.7.part.8+0x2cc/0x1918 > softirqs last disabled at (0): [<0000000000000000>] (null) > CPU: 5 PID: 554 Comm: ethtool Not tainted 4.17.0-rc4-arm64-renesas+ #33 > Hardware name: Renesas H3ULCB board based on r8a7795 ES2.0+ (DT) > Call trace: > dump_backtrace+0x0/0x198 > show_stack+0x24/0x30 > dump_stack+0xb8/0xf4 > ___might_sleep+0x1c8/0x1f8 > __might_sleep+0x58/0x90 > __mutex_lock+0x50/0x890 > mutex_lock_nested+0x3c/0x50 > phy_start_aneg_priv+0x38/0x180 > phy_start_aneg+0x24/0x30 > ravb_nway_reset+0x3c/0x68 > dev_ethtool+0x3dc/0x2338 > dev_ioctl+0x19c/0x490 > sock_do_ioctl+0xe0/0x238 > sock_ioctl+0x254/0x460 > do_vfs_ioctl+0xb0/0x918 > ksys_ioctl+0x50/0x80 > sys_ioctl+0x34/0x48 > __sys_trace_return+0x0/0x4 > > The root cause is that an attempt to modify ECMR and GECMR registers > only when RX/TX function is disabled was too overcomplicated in its > original implementation, also processing of an optional Link Change > interrupt added even more complexity, as a result the implementation > was error prone. > > The new locking scheme is confirmed to be correct by dumping driver > specific and generic PHY framework function calls with aid of ftrace > while running more or less advanced tests. > > Please note that sh_eth patches from the series were built-tested only. > > On purpose I do not add Fixes tags, the reused PHY handlers were added > way later than the fixed problems were firstly found in the drivers. I think you went one step too far with these fixes. On the first glance, the real fixes are to remove grabbing/releasing the spinlock for the duration of the phylib calls. Am I right? If so, making use of the new phylib APIs would be a further enhancement, it's not needed for fixing the splats per se... MBR, Sergei
