Hi, Please tell me what alternatives exists to replace wake_up/wait_event ? Thank you very much On 2/17/20, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > Laurentiu-Cristian Duca <laurentiu.duca@xxxxxxxxx> writes: >> I am an open source enthusiast and >> I have written a driver for Texas Instruments omap4 mcspi >> beaglebone black open source board, linux preempt_rt kernel 5.4.5-rt3. >> I have the following problem (if you want all the code >> I will post it, it is gpl open source): >> >> - in the interrupt I do >> mcspi->interrupt_done = 1; >> wake_up_interruptible(&mcspi->wq); >> >> - in the transfer function I do >> /* Enable interrupts last. */ >> mcspi->interrupt_done = 0; >> l = OMAP2_MCSPI_IRQENABLE_TX0_EMPTY | >> OMAP2_MCSPI_IRQENABLE_RX0_FULL; >> mcspi_write_reg(mcspi->master, OMAP2_MCSPI_IRQENABLE, l); >> >> /* TX_EMPTY will be raised only after SPI data is sent */ >> mcspi_wr_fifo(mcspi); >> >> /* wait for transfer completion */ >> wait_event_interruptible(mcspi->wq, (mcspi->interrupt_done > 0)); >> >> - I try to make one million small SPI transfers (8 bytes per transfer), >> but after about 10000 transfers I get kernel oops and then panic > > Not a surprise. > >> [ 166.994607] 000: PC is at rt_spin_lock_slowlock_locked+0x268/0x304 >> [ 167.391044] 000: [<c0909e40>] (rt_spin_lock_slowlock_locked) from >> [<c0909f30>] (rt_spin_lock_slowlock+0x54/0x7c) >> [ 167.401265] 000: [<c0909f30>] (rt_spin_lock_slowlock) from [<c01891bc>] >> (__wake_up_common_lock+0x58/0xa8) >> [ 167.410882] 000: [<c01891bc>] (__wake_up_common_lock) from [<c0189220>] >> (__wake_up+0x14/0x1c) >> [ 167.419445] 000: [<c0189220>] (__wake_up) from [<bf00056c>] >> (omap2_mcspi_irq_handler_rt+0xa4/0x118 [spi_omap2_mcspi]) >> [ 167.430114] 000: [<bf00056c>] (omap2_mcspi_irq_handler_rt >> [spi_omap2_mcspi]) from [<c019dfa0>] >> (__handle_irq_event_percpu+0x50/0x2c4) [ 167.442181] 000: [<c019dfa0>] >> (__handle_irq_event_percpu) from >> [<c019e280>] (handle_irq_event_percpu+0x6c/0xc4) [ 167.452315] 000: >> [<c019e280>] (handle_irq_event_percpu) from >> [<c019e344>] (handle_irq_event+0x6c/0xb0) [ 167.461663] 000: [<c019e344>] >> (handle_irq_event) from [<c01a28b0>] >> (handle_level_irq+0xdc/0x1bc) [ 167.470491] 000: [<c01a28b0>] >> (handle_level_irq) from [<c019d0dc>] >> (generic_handle_irq+0x20/0x34) [ 167.479403] 000: [<c019d0dc>] >> (generic_handle_irq) from > > You're using a interrupt with IRQF_NO_THREAD and call into a function > which is not safe to use from hard interrupt context on RT > i.e. wake_up(). Remove IRQF_NO_THREAD and your problem goes away. > > Thanks, > > tglx >
