24201a6477
The DMA error handler routine is currently a tasklet, scheduled to run after the DMA error IRQ was handled. However it needs to take the MDIO mutex, which is not allowed to do in a tasklet. A kernel (with debug options) complains consequently: [ 614.050361] net eth0: DMA Tx error 0x174019 [ 614.064002] net eth0: Current BD is at: 0x8f84aa0ce [ 614.080195] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:935 [ 614.109484] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 40, name: kworker/u4:4 [ 614.135428] 3 locks held by kworker/u4:4/40: [ 614.149075] #0: ffff000879863328 ((wq_completion)rpciod){....}, at: process_one_work+0x1f0/0x6a8 [ 614.177528] #1: ffff80001251bdf8 ((work_completion)(&task->u.tk_work)){....}, at: process_one_work+0x1f0/0x6a8 [ 614.209033] #2: ffff0008784e0110 (sk_lock-AF_INET-RPC){....}, at: tcp_sendmsg+0x24/0x58 [ 614.235429] CPU: 0 PID: 40 Comm: kworker/u4:4 Not tainted 5.6.0-rc3-00926-g4a165a9d5921 #26 [ 614.260854] Hardware name: ARM Test FPGA (DT) [ 614.274734] Workqueue: rpciod rpc_async_schedule [ 614.289022] Call trace: [ 614.296871] dump_backtrace+0x0/0x1a0 [ 614.308311] show_stack+0x14/0x20 [ 614.318751] dump_stack+0xbc/0x100 [ 614.329403] ___might_sleep+0xf0/0x140 [ 614.341018] __might_sleep+0x4c/0x80 [ 614.352201] __mutex_lock+0x5c/0x8a8 [ 614.363348] mutex_lock_nested+0x1c/0x28 [ 614.375654] axienet_dma_err_handler+0x38/0x388 [ 614.389999] tasklet_action_common.isra.15+0x160/0x1a8 [ 614.405894] tasklet_action+0x24/0x30 [ 614.417297] efi_header_end+0xe0/0x494 [ 614.429020] irq_exit+0xd0/0xd8 [ 614.439047] __handle_domain_irq+0x60/0xb0 [ 614.451877] gic_handle_irq+0xdc/0x2d0 [ 614.463486] el1_irq+0xcc/0x180 [ 614.473451] __tcp_transmit_skb+0x41c/0xb58 [ 614.486513] tcp_write_xmit+0x224/0x10a0 [ 614.498792] __tcp_push_pending_frames+0x38/0xc8 [ 614.513126] tcp_rcv_established+0x41c/0x820 [ 614.526301] tcp_v4_do_rcv+0x8c/0x218 [ 614.537784] __release_sock+0x5c/0x108 [ 614.549466] release_sock+0x34/0xa0 [ 614.560318] tcp_sendmsg+0x40/0x58 [ 614.571053] inet_sendmsg+0x40/0x68 [ 614.582061] sock_sendmsg+0x18/0x30 [ 614.593074] xs_sendpages+0x218/0x328 [ 614.604506] xs_tcp_send_request+0xa0/0x1b8 [ 614.617461] xprt_transmit+0xc8/0x4f0 [ 614.628943] call_transmit+0x8c/0xa0 [ 614.640028] __rpc_execute+0xbc/0x6f8 [ 614.651380] rpc_async_schedule+0x28/0x48 [ 614.663846] process_one_work+0x298/0x6a8 [ 614.676299] worker_thread+0x40/0x490 [ 614.687687] kthread+0x134/0x138 [ 614.697804] ret_from_fork+0x10/0x18 [ 614.717319] xilinx_axienet 7fe00000.ethernet eth0: Link is Down [ 615.748343] xilinx_axienet 7fe00000.ethernet eth0: Link is Up - 1Gbps/Full - flow control off Since tasklets are not really popular anymore anyway, lets convert this over to a work queue, which can sleep and thus can take the MDIO mutex. Signed-off-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.