drivers: net: davinci_cpdma: remove spinlock as SOFTIRQ-unsafe lock order detected

remove spinlock in cpdma_desc_pool_destroy() as there is no active cpdma
channel and iounmap should be called without auquiring lock.

root@dra7xx-evm:~# modprobe -r ti_cpsw
[   50.539743]
[   50.541312] ======================================================
[   50.547796] [ INFO: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected ]
[   50.554826] 3.14.19-02124-g95c5b7b #308 Not tainted
[   50.559939] ------------------------------------------------------
[   50.566416] modprobe/1921 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
[   50.573347]  (vmap_area_lock){+.+...}, at: [<c01127fc>] find_vmap_area+0x10/0x6c
[   50.581132]
[   50.581132] and this task is already holding:
[   50.587249]  (&(&pool->lock)->rlock#2){..-...}, at: [<bf017c74>] cpdma_ctlr_destroy+0x5c/0x114 [davinci_cpdma]
[   50.597766] which would create a new lock dependency:
[   50.603048]  (&(&pool->lock)->rlock#2){..-...} -> (vmap_area_lock){+.+...}
[   50.610296]
[   50.610296] but this new dependency connects a SOFTIRQ-irq-safe lock:
[   50.618601]  (&(&pool->lock)->rlock#2){..-...}
... which became SOFTIRQ-irq-safe at:
[   50.626829]   [<c06585a4>] _raw_spin_lock_irqsave+0x38/0x4c
[   50.632677]   [<bf01773c>] cpdma_desc_free.constprop.7+0x28/0x58 [davinci_cpdma]
[   50.640437]   [<bf0177e8>] __cpdma_chan_free+0x7c/0xa8 [davinci_cpdma]
[   50.647289]   [<bf017908>] __cpdma_chan_process+0xf4/0x134 [davinci_cpdma]
[   50.654512]   [<bf017984>] cpdma_chan_process+0x3c/0x54 [davinci_cpdma]
[   50.661455]   [<bf0277e8>] cpsw_poll+0x14/0xa8 [ti_cpsw]
[   50.667038]   [<c05844f4>] net_rx_action+0xc0/0x1e8
[   50.672150]   [<c0048234>] __do_softirq+0xcc/0x304
[   50.677183]   [<c004873c>] irq_exit+0xa8/0xfc
[   50.681751]   [<c000eeac>] handle_IRQ+0x50/0xb0
[   50.686513]   [<c0008638>] gic_handle_irq+0x28/0x5c
[   50.691628]   [<c06590a4>] __irq_svc+0x44/0x5c
[   50.696289]   [<c0658ab4>] _raw_spin_unlock_irqrestore+0x34/0x44
[   50.702591]   [<c065a9c4>] do_page_fault.part.9+0x144/0x3c4
[   50.708433]   [<c065acb8>] do_page_fault+0x74/0x84
[   50.713453]   [<c00083dc>] do_DataAbort+0x34/0x98
[   50.718391]   [<c065923c>] __dabt_usr+0x3c/0x40
[   50.723148]
[   50.723148] to a SOFTIRQ-irq-unsafe lock:
[   50.728893]  (vmap_area_lock){+.+...}
... which became SOFTIRQ-irq-unsafe at:
[   50.736476] ...  [<c06584e8>] _raw_spin_lock+0x28/0x38
[   50.741876]   [<c011376c>] alloc_vmap_area.isra.28+0xb8/0x300
[   50.747908]   [<c0113a44>] __get_vm_area_node.isra.29+0x90/0x134
[   50.754210]   [<c011486c>] get_vm_area_caller+0x3c/0x48
[   50.759692]   [<c0114be0>] vmap+0x40/0x78
[   50.763900]   [<c09442f0>] check_writebuffer_bugs+0x54/0x1a0
[   50.769835]   [<c093eac0>] start_kernel+0x320/0x388
[   50.774952]   [<80008074>] 0x80008074
[   50.778793]
[   50.778793] other info that might help us debug this:
[   50.778793]
[   50.787181]  Possible interrupt unsafe locking scenario:
[   50.787181]
[   50.794295]        CPU0                    CPU1
[   50.799042]        ----                    ----
[   50.803785]   lock(vmap_area_lock);
[   50.807446]                                local_irq_disable();
[   50.813652]                                lock(&(&pool->lock)->rlock#2);
[   50.820782]                                lock(vmap_area_lock);
[   50.827086]   <Interrupt>
[   50.829823]     lock(&(&pool->lock)->rlock#2);
[   50.834490]
[   50.834490]  *** DEADLOCK ***
[   50.834490]
[   50.840695] 4 locks held by modprobe/1921:
[   50.844981]  #0:  (&__lockdep_no_validate__){......}, at: [<c03e53e8>] driver_detach+0x44/0xb8
[   50.854038]  #1:  (&__lockdep_no_validate__){......}, at: [<c03e53f4>] driver_detach+0x50/0xb8
[   50.863102]  #2:  (&(&ctlr->lock)->rlock){......}, at: [<bf017c34>] cpdma_ctlr_destroy+0x1c/0x114 [davinci_cpdma]
[   50.873890]  #3:  (&(&pool->lock)->rlock#2){..-...}, at: [<bf017c74>] cpdma_ctlr_destroy+0x5c/0x114 [davinci_cpdma]
[   50.884871]
the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
[   50.892827] -> (&(&pool->lock)->rlock#2){..-...} ops: 167 {
[   50.898703]    IN-SOFTIRQ-W at:
[   50.901995]                     [<c06585a4>] _raw_spin_lock_irqsave+0x38/0x4c
[   50.909476]                     [<bf01773c>] cpdma_desc_free.constprop.7+0x28/0x58 [davinci_cpdma]
[   50.918878]                     [<bf0177e8>] __cpdma_chan_free+0x7c/0xa8 [davinci_cpdma]
[   50.927366]                     [<bf017908>] __cpdma_chan_process+0xf4/0x134 [davinci_cpdma]
[   50.936218]                     [<bf017984>] cpdma_chan_process+0x3c/0x54 [davinci_cpdma]
[   50.944794]                     [<bf0277e8>] cpsw_poll+0x14/0xa8 [ti_cpsw]
[   50.952009]                     [<c05844f4>] net_rx_action+0xc0/0x1e8
[   50.958765]                     [<c0048234>] __do_softirq+0xcc/0x304
[   50.965432]                     [<c004873c>] irq_exit+0xa8/0xfc
[   50.971635]                     [<c000eeac>] handle_IRQ+0x50/0xb0
[   50.978035]                     [<c0008638>] gic_handle_irq+0x28/0x5c
[   50.984788]                     [<c06590a4>] __irq_svc+0x44/0x5c
[   50.991085]                     [<c0658ab4>] _raw_spin_unlock_irqrestore+0x34/0x44
[   50.999023]                     [<c065a9c4>] do_page_fault.part.9+0x144/0x3c4
[   51.006510]                     [<c065acb8>] do_page_fault+0x74/0x84
[   51.013171]                     [<c00083dc>] do_DataAbort+0x34/0x98
[   51.019738]                     [<c065923c>] __dabt_usr+0x3c/0x40
[   51.026129]    INITIAL USE at:
[   51.029335]                    [<c06585a4>] _raw_spin_lock_irqsave+0x38/0x4c
[   51.036729]                    [<bf017d78>] cpdma_chan_submit+0x4c/0x2f0 [davinci_cpdma]
[   51.045225]                    [<bf02863c>] cpsw_ndo_open+0x378/0x6bc [ti_cpsw]
[   51.052897]                    [<c058747c>] __dev_open+0x9c/0x104
[   51.059287]                    [<c05876ec>] __dev_change_flags+0x88/0x160
[   51.066420]                    [<c05877e4>] dev_change_flags+0x18/0x48
[   51.073270]                    [<c05ed51c>] devinet_ioctl+0x61c/0x6e0
[   51.080029]                    [<c056ee54>] sock_ioctl+0x5c/0x298
[   51.086418]                    [<c01350a4>] do_vfs_ioctl+0x78/0x61c
[   51.092993]                    [<c01356ac>] SyS_ioctl+0x64/0x74
[   51.099200]                    [<c000e580>] ret_fast_syscall+0x0/0x48
[   51.105956]  }
[   51.107696]  ... key      at: [<bf019000>] __key.21312+0x0/0xfffff650 [davinci_cpdma]
[   51.115912]  ... acquired at:
[   51.119019]    [<c00899ac>] lock_acquire+0x9c/0x104
[   51.124138]    [<c06584e8>] _raw_spin_lock+0x28/0x38
[   51.129341]    [<c01127fc>] find_vmap_area+0x10/0x6c
[   51.134547]    [<c0114960>] remove_vm_area+0x8/0x6c
[   51.139659]    [<c0114a7c>] __vunmap+0x20/0xf8
[   51.144318]    [<c001c350>] __arm_iounmap+0x10/0x18
[   51.149440]    [<bf017d08>] cpdma_ctlr_destroy+0xf0/0x114 [davinci_cpdma]
[   51.156560]    [<bf026294>] cpsw_remove+0x48/0x8c [ti_cpsw]
[   51.162407]    [<c03e62c8>] platform_drv_remove+0x18/0x1c
[   51.168063]    [<c03e4c44>] __device_release_driver+0x70/0xc8
[   51.174094]    [<c03e5458>] driver_detach+0xb4/0xb8
[   51.179212]    [<c03e4a6c>] bus_remove_driver+0x4c/0x90
[   51.184693]    [<c00b024c>] SyS_delete_module+0x10c/0x198
[   51.190355]    [<c000e580>] ret_fast_syscall+0x0/0x48
[   51.195661]
[   51.197217]
the dependencies between the lock to be acquired and SOFTIRQ-irq-unsafe lock:
[   51.205986] -> (vmap_area_lock){+.+...} ops: 520 {
[   51.211032]    HARDIRQ-ON-W at:
[   51.214321]                     [<c06584e8>] _raw_spin_lock+0x28/0x38
[   51.221090]                     [<c011376c>] alloc_vmap_area.isra.28+0xb8/0x300
[   51.228750]                     [<c0113a44>] __get_vm_area_node.isra.29+0x90/0x134
[   51.236690]                     [<c011486c>] get_vm_area_caller+0x3c/0x48
[   51.243811]                     [<c0114be0>] vmap+0x40/0x78
[   51.249654]                     [<c09442f0>] check_writebuffer_bugs+0x54/0x1a0
[   51.257239]                     [<c093eac0>] start_kernel+0x320/0x388
[   51.263994]                     [<80008074>] 0x80008074
[   51.269474]    SOFTIRQ-ON-W at:
[   51.272769]                     [<c06584e8>] _raw_spin_lock+0x28/0x38
[   51.279525]                     [<c011376c>] alloc_vmap_area.isra.28+0xb8/0x300
[   51.287190]                     [<c0113a44>] __get_vm_area_node.isra.29+0x90/0x134
[   51.295126]                     [<c011486c>] get_vm_area_caller+0x3c/0x48
[   51.302245]                     [<c0114be0>] vmap+0x40/0x78
[   51.308094]                     [<c09442f0>] check_writebuffer_bugs+0x54/0x1a0
[   51.315669]                     [<c093eac0>] start_kernel+0x320/0x388
[   51.322423]                     [<80008074>] 0x80008074
[   51.327906]    INITIAL USE at:
[   51.331112]                    [<c06584e8>] _raw_spin_lock+0x28/0x38
[   51.337775]                    [<c011376c>] alloc_vmap_area.isra.28+0xb8/0x300
[   51.345352]                    [<c0113a44>] __get_vm_area_node.isra.29+0x90/0x134
[   51.353197]                    [<c011486c>] get_vm_area_caller+0x3c/0x48
[   51.360224]                    [<c0114be0>] vmap+0x40/0x78
[   51.365977]                    [<c09442f0>] check_writebuffer_bugs+0x54/0x1a0
[   51.373464]                    [<c093eac0>] start_kernel+0x320/0x388
[   51.380131]                    [<80008074>] 0x80008074
[   51.385517]  }
[   51.387260]  ... key      at: [<c0a66948>] vmap_area_lock+0x10/0x20
[   51.393841]  ... acquired at:
[   51.396945]    [<c00899ac>] lock_acquire+0x9c/0x104
[   51.402060]    [<c06584e8>] _raw_spin_lock+0x28/0x38
[   51.407266]    [<c01127fc>] find_vmap_area+0x10/0x6c
[   51.412478]    [<c0114960>] remove_vm_area+0x8/0x6c
[   51.417592]    [<c0114a7c>] __vunmap+0x20/0xf8
[   51.422252]    [<c001c350>] __arm_iounmap+0x10/0x18
[   51.427369]    [<bf017d08>] cpdma_ctlr_destroy+0xf0/0x114 [davinci_cpdma]
[   51.434487]    [<bf026294>] cpsw_remove+0x48/0x8c [ti_cpsw]
[   51.440336]    [<c03e62c8>] platform_drv_remove+0x18/0x1c
[   51.446000]    [<c03e4c44>] __device_release_driver+0x70/0xc8
[   51.452031]    [<c03e5458>] driver_detach+0xb4/0xb8
[   51.457147]    [<c03e4a6c>] bus_remove_driver+0x4c/0x90
[   51.462628]    [<c00b024c>] SyS_delete_module+0x10c/0x198
[   51.468289]    [<c000e580>] ret_fast_syscall+0x0/0x48
[   51.473584]
[   51.475140]
[   51.475140] stack backtrace:
[   51.479703] CPU: 0 PID: 1921 Comm: modprobe Not tainted 3.14.19-02124-g95c5b7b #308
[   51.487744] [<c0016090>] (unwind_backtrace) from [<c0012060>] (show_stack+0x10/0x14)
[   51.495865] [<c0012060>] (show_stack) from [<c0652a20>] (dump_stack+0x78/0x94)
[   51.503444] [<c0652a20>] (dump_stack) from [<c0086f18>] (check_usage+0x408/0x594)
[   51.511293] [<c0086f18>] (check_usage) from [<c00870f8>] (check_irq_usage+0x54/0xb0)
[   51.519416] [<c00870f8>] (check_irq_usage) from [<c0088724>] (__lock_acquire+0xe54/0x1b90)
[   51.528077] [<c0088724>] (__lock_acquire) from [<c00899ac>] (lock_acquire+0x9c/0x104)
[   51.536291] [<c00899ac>] (lock_acquire) from [<c06584e8>] (_raw_spin_lock+0x28/0x38)
[   51.544417] [<c06584e8>] (_raw_spin_lock) from [<c01127fc>] (find_vmap_area+0x10/0x6c)
[   51.552726] [<c01127fc>] (find_vmap_area) from [<c0114960>] (remove_vm_area+0x8/0x6c)
[   51.560935] [<c0114960>] (remove_vm_area) from [<c0114a7c>] (__vunmap+0x20/0xf8)
[   51.568693] [<c0114a7c>] (__vunmap) from [<c001c350>] (__arm_iounmap+0x10/0x18)
[   51.576362] [<c001c350>] (__arm_iounmap) from [<bf017d08>] (cpdma_ctlr_destroy+0xf0/0x114 [davinci_cpdma])
[   51.586494] [<bf017d08>] (cpdma_ctlr_destroy [davinci_cpdma]) from [<bf026294>] (cpsw_remove+0x48/0x8c [ti_cpsw])
[   51.597261] [<bf026294>] (cpsw_remove [ti_cpsw]) from [<c03e62c8>] (platform_drv_remove+0x18/0x1c)
[   51.606659] [<c03e62c8>] (platform_drv_remove) from [<c03e4c44>] (__device_release_driver+0x70/0xc8)
[   51.616237] [<c03e4c44>] (__device_release_driver) from [<c03e5458>] (driver_detach+0xb4/0xb8)
[   51.625264] [<c03e5458>] (driver_detach) from [<c03e4a6c>] (bus_remove_driver+0x4c/0x90)
[   51.633749] [<c03e4a6c>] (bus_remove_driver) from [<c00b024c>] (SyS_delete_module+0x10c/0x198)
[   51.642781] [<c00b024c>] (SyS_delete_module) from [<c000e580>] (ret_fast_syscall+0x0/0x48)

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>