On 19. 12. 24, 13:42, Zhongqiu Han wrote:
It is considered good practice to call cpu_relax() in busy loops, see
Documentation/process/volatile-considered-harmful.rst. This can lower CPU
power consumption or yield to a hyperthreaded twin processor, or serve as
a compiler barrier. In addition, if something goes wrong in the busy loop
at least it can prevent things from getting worse.
Signed-off-by: Zhongqiu Han <quic_zhonhan@xxxxxxxxxxx>
---
drivers/tty/mips_ejtag_fdc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/mips_ejtag_fdc.c b/drivers/tty/mips_ejtag_fdc.c
index afbf7738c7c4..b17ead1e9698 100644
--- a/drivers/tty/mips_ejtag_fdc.c
+++ b/drivers/tty/mips_ejtag_fdc.c
@@ -346,7 +346,7 @@ static void mips_ejtag_fdc_console_write(struct console *c, const char *s,
/* Busy wait until there's space in fifo */
while (__raw_readl(regs + REG_FDSTAT) & REG_FDSTAT_TXF)
- ;
+ cpu_relax();
__raw_writel(word.word, regs + REG_FDTX(c->index));
}
out:
@@ -1233,7 +1233,7 @@ static void kgdbfdc_push_one(void)
/* Busy wait until there's space in fifo */
while (__raw_readl(regs + REG_FDSTAT) & REG_FDSTAT_TXF)
- ;
+ cpu_relax();
Can this instead be switched to read_poll_timeout_atomic() or alike?
Those already contain cpu_relax(), of course...
thanks,
--
js
suse labs
