Re: [PATCH net 1/6] can: m_can: m_can_class_allocate_dev(): initialize spin lock on device probe

[Jacob Keller <jacob.e.keller@intel.com>]

On 5/6/2025 6:56 AM, Marc Kleine-Budde wrote:
> From: Antonios Salios <antonios@mwa.re>
> 
> The spin lock tx_handling_spinlock in struct m_can_classdev is not
> being initialized. This leads the following spinlock bad magic
> complaint from the kernel, eg. when trying to send CAN frames with
> cansend from can-utils:
> 
> | BUG: spinlock bad magic on CPU#0, cansend/95
> |  lock: 0xff60000002ec1010, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
> | CPU: 0 UID: 0 PID: 95 Comm: cansend Not tainted 6.15.0-rc3-00032-ga79be02bba5c #5 NONE
> | Hardware name: MachineWare SIM-V (DT)
> | Call Trace:
> | [<ffffffff800133e0>] dump_backtrace+0x1c/0x24
> | [<ffffffff800022f2>] show_stack+0x28/0x34
> | [<ffffffff8000de3e>] dump_stack_lvl+0x4a/0x68
> | [<ffffffff8000de70>] dump_stack+0x14/0x1c
> | [<ffffffff80003134>] spin_dump+0x62/0x6e
> | [<ffffffff800883ba>] do_raw_spin_lock+0xd0/0x142
> | [<ffffffff807a6fcc>] _raw_spin_lock_irqsave+0x20/0x2c
> | [<ffffffff80536dba>] m_can_start_xmit+0x90/0x34a
> | [<ffffffff806148b0>] dev_hard_start_xmit+0xa6/0xee
> | [<ffffffff8065b730>] sch_direct_xmit+0x114/0x292
> | [<ffffffff80614e2a>] __dev_queue_xmit+0x3b0/0xaa8
> | [<ffffffff8073b8fa>] can_send+0xc6/0x242
> | [<ffffffff8073d1c0>] raw_sendmsg+0x1a8/0x36c
> | [<ffffffff805ebf06>] sock_write_iter+0x9a/0xee
> | [<ffffffff801d06ea>] vfs_write+0x184/0x3a6
> | [<ffffffff801d0a88>] ksys_write+0xa0/0xc0
> | [<ffffffff801d0abc>] __riscv_sys_write+0x14/0x1c
> | [<ffffffff8079ebf8>] do_trap_ecall_u+0x168/0x212
> | [<ffffffff807a830a>] handle_exception+0x146/0x152
> 
> Initializing the spin lock in m_can_class_allocate_dev solves that
> problem.
> 
> Fixes: 1fa80e23c150 ("can: m_can: Introduce a tx_fifo_in_flight counter")
> Signed-off-by: Antonios Salios <antonios@mwa.re>
> Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
> Link: https://patch.msgid.link/20250425111744.37604-2-antonios@mwa.re
> Reviewed-by: Markus Schneider-Pargmann <msp@baylibre.com>
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
> ---

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>