From a9ddc71f5840c2711e530f2e055b278f79948b29 Mon Sep 17 00:00:00 2001 From: Mathieu Poirier Date: Tue, 2 Feb 2016 14:13:56 -0700 Subject: [PATCH] coresight: fixing lockdep error On some platform the following lockdep error occurs when doing simple manipulations: [ 23.197021] [ 23.198608] ====================================================== [ 23.205078] [ INFO: possible circular locking dependency detected ] [ 23.211639] 4.4.0-rc8-00025-gbbf360b #172 Not tainted [ 23.216918] ------------------------------------------------------- [ 23.223480] sh/858 is trying to acquire lock: [ 23.228057] (coresight_mutex){+.+.+.}, at: [] coresight_enable+0x1c/0x1b4 [ 23.236206] [ 23.236206] but task is already holding lock: [ 23.242309] (s_active#52){++++.+}, at: [] kernfs_fop_write+0x5c/0x1c0 [ 23.250122] [ 23.250122] which lock already depends on the new lock. [ 23.250122] [ 23.258697] [ 23.258697] the existing dependency chain (in reverse order) is: [ 23.266510] -> #1 (s_active#52){++++.+}: [ 23.270843] [] __kernfs_remove+0x294/0x35c [ 23.276672] [] kernfs_remove_by_name_ns+0x44/0x8c [ 23.283172] [] remove_files+0x3c/0x84 [ 23.288543] [] sysfs_remove_group+0x48/0x9c [ 23.294494] [] sysfs_remove_groups+0x2c/0x3c [ 23.300506] [] device_remove_attrs+0x5c/0x74 [ 23.306549] [] device_del+0x110/0x218 [ 23.311950] [] device_unregister+0x2c/0x6c [ 23.317779] [] coresight_unregister+0x30/0x40 [ 23.323883] [] etm_probe+0x228/0x2e8 [ 23.329193] [] amba_probe+0xe4/0x160 [ 23.334503] [] driver_probe_device+0x23c/0x480 [ 23.340728] [] __driver_attach+0x9c/0xa0 [ 23.346374] [] bus_for_each_dev+0x70/0xa4 [ 23.352142] [] driver_attach+0x24/0x28 [ 23.357604] [] bus_add_driver+0x1e0/0x278 [ 23.363372] [] driver_register+0x80/0x100 [ 23.369110] [] amba_driver_register+0x58/0x5c [ 23.375244] [] etm_driver_init+0x18/0x1c [ 23.380889] [] do_one_initcall+0xc4/0x20c [ 23.386657] [] kernel_init_freeable+0x160/0x208 [ 23.392974] [] kernel_init+0x18/0xf0 [ 23.398254] [] ret_from_fork+0x14/0x24 [ 23.403747] -> #0 (coresight_mutex){+.+.+.}: [ 23.408447] [] lock_acquire+0xe4/0x210 [ 23.413909] [] mutex_lock_nested+0x74/0x450 [ 23.419860] [] coresight_enable+0x1c/0x1b4 [ 23.425689] [] enable_source_store+0x58/0x68 [ 23.431732] [] dev_attr_store+0x20/0x2c [ 23.437286] [] sysfs_kf_write+0x50/0x54 [ 23.442871] [] kernfs_fop_write+0xc4/0x1c0 [ 23.448699] [] __vfs_write+0x34/0xe4 [ 23.454040] [] vfs_write+0x98/0x174 [ 23.459228] [] SyS_write+0x4c/0xa8 [ 23.464355] [] ret_fast_syscall+0x0/0x1c [ 23.470031] [ 23.470031] other info that might help us debug this: [ 23.470031] [ 23.478393] Possible unsafe locking scenario: [ 23.478393] [ 23.484619] CPU0 CPU1 [ 23.489349] ---- ---- [ 23.494079] lock(s_active#52); [ 23.497497] lock(coresight_mutex); [ 23.503906] lock(s_active#52); [ 23.509918] lock(coresight_mutex); [ 23.513702] [ 23.513702] *** DEADLOCK *** [ 23.513702] [ 23.519897] 3 locks held by sh/858: [ 23.523529] #0: (sb_writers#7){.+.+.+}, at: [] __sb_start_write+0xa8/0xd4 [ 23.531799] #1: (&of->mutex){+.+...}, at: [] kernfs_fop_write+0x54/0x1c0 [ 23.539916] #2: (s_active#52){++++.+}, at: [] kernfs_fop_write+0x5c/0x1c0 [ 23.548156] [ 23.548156] stack backtrace: [ 23.552734] CPU: 0 PID: 858 Comm: sh Not tainted 4.4.0-rc8-00025-gbbf360b #172 [ 23.560302] Hardware name: Generic OMAP4 (Flattened Device Tree) [ 23.566589] Backtrace: [ 23.569152] [] (dump_backtrace) from [] (show_stack+0x18/0x1c) [ 23.577087] r7:ed4b8570 r6:c0936400 r5:c07ae71c r4:00000000 [ 23.583038] [] (show_stack) from [] (dump_stack+0x98/0xc0) [ 23.590606] [] (dump_stack) from [] (print_circular_bug+0x21c/0x33c) [ 23.599090] r5:c0939d60 r4:c0936400 [ 23.602874] [] (print_circular_bug) from [] (__lock_acquire+0x1c98/0x1d88) [ 23.611877] r10:00000003 r9:c0fd7a5c r8:ed4b8550 r7:ed4b8570 r6:ed4b8000 r5:c0ff69e4 [ 23.620117] r4:c0936400 r3:ed4b8550 [ 23.623901] [] (__lock_acquire) from [] (lock_acquire+0xe4/0x210) [ 23.632080] r10:00000000 r9:00000000 r8:60000013 r7:c07cb7b4 r6:00000001 r5:00000000 [ 23.640350] r4:00000000 [ 23.643005] [] (lock_acquire) from [] (mutex_lock_nested+0x74/0x450) [ 23.651458] r10:ecc0bf80 r9:edbe7dcc r8:ed4b8000 r7:c0fd7a5c r6:c0415d40 r5:00000000 [ 23.659729] r4:c07cb780 [ 23.662384] [] (mutex_lock_nested) from [] (coresight_enable+0x1c/0x1b4) [ 23.671234] r10:ecc0bf80 r9:edbe7dcc r8:ed733c00 r7:00000000 r6:ed733c00 r5:00000002 [ 23.679473] r4:ed762140 [ 23.682128] [] (coresight_enable) from [] (enable_source_store+0x58/0x68) [ 23.691070] r7:00000000 r6:ed733c00 r5:00000002 r4:ed762160 [ 23.697052] [] (enable_source_store) from [] (dev_attr_store+0x20/0x2c) [ 23.705780] r5:edbe7dc0 r4:c0415fd8 [ 23.709533] [] (dev_attr_store) from [] (sysfs_kf_write+0x50/0x54) [ 23.717834] r5:edbe7dc0 r4:c030b338 [ 23.721618] [] (sysfs_kf_write) from [] (kernfs_fop_write+0xc4/0x1c0) [ 23.730163] r7:00000000 r6:00000000 r5:00000002 r4:edbe7dc0 [ 23.736145] [] (kernfs_fop_write) from [] (__vfs_write+0x34/0xe4) [ 23.744323] r10:00000000 r9:ecc0a000 r8:c0010964 r7:ecc0bf80 r6:00000002 r5:c01d4ae4 [ 23.752593] r4:ee385a40 [ 23.755249] [] (__vfs_write) from [] (vfs_write+0x98/0x174) [ 23.762908] r9:ecc0a000 r8:c0010964 r7:ecc0bf80 r6:000ab0d8 r5:00000002 r4:ee385a40 [ 23.771057] [] (vfs_write) from [] (SyS_write+0x4c/0xa8) [ 23.778442] r8:c0010964 r7:00000002 r6:000ab0d8 r5:ee385a40 r4:ee385a40 [ 23.785522] [] (SyS_write) from [] (ret_fast_syscall+0x0/0x1c) [ 23.793457] r7:00000004 r6:00000001 r5:000ab0d8 r4:00000002 [ 23.799652] coresight-etb10 54162000.etb: ETB enabled [ 23.805084] coresight-funnel 54164000.funnel: FUNNEL inport 0 enabled [ 23.811859] coresight-replicator 44000000.ocp:replicator: REPLICATOR enabled [ 23.819335] coresight-funnel 54158000.funnel: FUNNEL inport 0 enabled [ 23.826110] coresight-etm3x 5414c000.ptm: ETM tracing enabled The locking in coresight_unregister() is not required as the only customers of the function are drivers themselves when an initialisation failure has been encoutered. Reported-by: Rabin Vincent Signed-off-by: Mathieu Poirier Signed-off-by: Greg Kroah-Hartman --- drivers/hwtracing/coresight/coresight.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c index 4236a02cdab2..41b42018b660 100644 --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -713,12 +713,8 @@ EXPORT_SYMBOL_GPL(coresight_register); void coresight_unregister(struct coresight_device *csdev) { - mutex_lock(&coresight_mutex); - kfree(csdev->conns); device_unregister(&csdev->dev); - - mutex_unlock(&coresight_mutex); } EXPORT_SYMBOL_GPL(coresight_unregister);