From: Huisong Li lihuisong@huawei.com
[ Upstream commit 9779d45c749340ab461d595c1a4a664cb28f3007 ]
The function mbox_chan_received_data() calls the Rx callback of the mailbox client driver. The callback might set chan_in_use flag from pcc_send_data(). This flag's status determines whether the PCC channel is in use.
However, there is a potential race condition where chan_in_use is updated incorrectly due to concurrency between the interrupt handler (pcc_mbox_irq()) and the command sender(pcc_send_data()).
The 'chan_in_use' flag of a channel is set to true after sending a command. And the flag of the new command may be cleared erroneous by the interrupt handler afer mbox_chan_received_data() returns,
As a result, the interrupt being level triggered can't be cleared in pcc_mbox_irq() and it will be disabled after the number of handled times exceeds the specified value. The error log is as follows:
| kunpeng_hccs HISI04B2:00: PCC command executed timeout! | kunpeng_hccs HISI04B2:00: get port link status info failed, ret = -110 | irq 13: nobody cared (try booting with the "irqpoll" option) | Call trace: | dump_backtrace+0x0/0x210 | show_stack+0x1c/0x2c | dump_stack+0xec/0x130 | __report_bad_irq+0x50/0x190 | note_interrupt+0x1e4/0x260 | handle_irq_event+0x144/0x17c | handle_fasteoi_irq+0xd0/0x240 | __handle_domain_irq+0x80/0xf0 | gic_handle_irq+0x74/0x2d0 | el1_irq+0xbc/0x140 | mnt_clone_write+0x0/0x70 | file_update_time+0xcc/0x160 | fault_dirty_shared_page+0xe8/0x150 | do_shared_fault+0x80/0x1d0 | do_fault+0x118/0x1a4 | handle_pte_fault+0x154/0x230 | __handle_mm_fault+0x1ac/0x390 | handle_mm_fault+0xf0/0x250 | do_page_fault+0x184/0x454 | do_translation_fault+0xac/0xd4 | do_mem_abort+0x44/0xb4 | el0_da+0x40/0x74 | el0_sync_handler+0x60/0xb4 | el0_sync+0x168/0x180 | handlers: | pcc_mbox_irq | Disabling IRQ #13
To solve this issue, pcc_mbox_irq() must clear 'chan_in_use' flag before the call to mbox_chan_received_data().
Tested-by: Adam Young admiyo@os.amperecomputing.com Tested-by: Robbie King robbiek@xsightlabs.com Signed-off-by: Huisong Li lihuisong@huawei.com (sudeep.holla: Minor updates to the subject, commit message and comment) Signed-off-by: Sudeep Holla sudeep.holla@arm.com Signed-off-by: Jassi Brar jassisinghbrar@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/mailbox/pcc.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c index 82102a4c5d688..8fd4d0f79b090 100644 --- a/drivers/mailbox/pcc.c +++ b/drivers/mailbox/pcc.c @@ -333,10 +333,16 @@ static irqreturn_t pcc_mbox_irq(int irq, void *p) if (pcc_chan_reg_read_modify_write(&pchan->plat_irq_ack)) return IRQ_NONE;
+ /* + * Clear this flag after updating interrupt ack register and just + * before mbox_chan_received_data() which might call pcc_send_data() + * where the flag is set again to start new transfer. This is + * required to avoid any possible race in updatation of this flag. + */ + pchan->chan_in_use = false; mbox_chan_received_data(chan, NULL);
check_and_ack(pchan, chan); - pchan->chan_in_use = false;
return IRQ_HANDLED; }