On 05/24/2018 07:40 PM, Sergei Shtylyov 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... Note that I hadn't looked at the patches #3/#6 at the time of writing this; those seem to be more complicated than the rest. MBR, Sergei
