4.14-stable review patch. If anyone has any objections, please let me know.
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From: Janek Kotas jank@cadence.com
commit 931c4e9a72ae91d59c5332ffb6812911a749da8e upstream.
The path "spi: cadence: Add usleep_range() for cdns_spi_fill_tx_fifo()" added a usleep_range() function call, which cannot be used in atomic context. However the cdns_spi_fill_tx_fifo() function can be called during an interrupt which may result in a kernel panic:
BUG: scheduling while atomic: grep/561/0x00010002 Modules linked in: Preemption disabled at: [<ffffff800858ea28>] wait_for_common+0x48/0x178 CPU: 0 PID: 561 Comm: grep Not tainted 4.17.0 #1 Hardware name: Cadence CSP (DT) Call trace: dump_backtrace+0x0/0x198 show_stack+0x14/0x20 dump_stack+0x8c/0xac __schedule_bug+0x6c/0xb8 __schedule+0x570/0x5d8 schedule+0x34/0x98 schedule_hrtimeout_range_clock+0x98/0x110 schedule_hrtimeout_range+0x10/0x18 usleep_range+0x64/0x98 cdns_spi_fill_tx_fifo+0x70/0xb0 cdns_spi_irq+0xd0/0xe0 __handle_irq_event_percpu+0x9c/0x128 handle_irq_event_percpu+0x34/0x88 handle_irq_event+0x48/0x78 handle_fasteoi_irq+0xbc/0x1b0 generic_handle_irq+0x24/0x38 __handle_domain_irq+0x84/0xf8 gic_handle_irq+0xc4/0x180
This patch replaces the function call with udelay() which can be used in an atomic context, like an interrupt.
Signed-off-by: Jan Kotas jank@cadence.com Signed-off-by: Mark Brown broonie@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/spi/spi-cadence.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/spi/spi-cadence.c +++ b/drivers/spi/spi-cadence.c @@ -319,7 +319,7 @@ static void cdns_spi_fill_tx_fifo(struct */ if (cdns_spi_read(xspi, CDNS_SPI_ISR) & CDNS_SPI_IXR_TXFULL) - usleep_range(10, 20); + udelay(10);
if (xspi->txbuf) cdns_spi_write(xspi, CDNS_SPI_TXD, *xspi->txbuf++);