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Michael Holzheu authored
The debug_register/unregister_view() functions call debugfs_remove() while holding the debug_info spinlock. Because debugfs_remove() takes a mutex and therefore can sleep this is not allowed. To fix the problem we give up the debug_info lock before calling debugfs_remove(). The following shows the lockdep message: [ INFO: possible circular locking dependency detected ] ------------------------------------------------------- rmmod/4379 is trying to acquire lock: (&sb->s_type->i_mutex_key#2){+.+.+.}, at: [<00000000003acae2>] debugfs_remove+0x5e/0xa but task is already holding lock: (&(&rc->lock)->rlock){-.-...}, at: [<000000000010a5ae>] debug_unregister_view+0x3a/0xd which lock already depends on the new lock. -> #0 (&sb->s_type->i_mutex_key#2){+.+.+.}: [<00000000001b1644>] validate_chain+0x880/0x1154 [<00000000001b4d6c>] __lock_acquire+0x414/0xc44 [<00000000001b5c16>] lock_acquire+0xbe/0x178 [<0000000000614016>] mutex_lock_nested+0x66/0x36c [<00000000003acae2>] debugfs_remove+0x5e/0xac [<000000000010a620>] debug_unregister_view+0xac/0xd0 [<000003ff8002f140>] qeth_core_exit+0x48/0xf08 [qeth] [<00000000001c35a4>] SyS_delete_module+0x1a4/0x260 [<0000000000618134>] sysc_noemu+0x22/0x28 [<000003fffd4704da>] 0x3fffd4704da Signed-off-by:
Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by:
Martin Schwidefsky <schwidefsky@de.ibm.com>
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