diff options
Diffstat (limited to 'include/linux/iopoll.h')
| -rw-r--r-- | include/linux/iopoll.h | 74 |
1 files changed, 44 insertions, 30 deletions
diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h index 2c8860e406bd..91324c331a4b 100644 --- a/include/linux/iopoll.h +++ b/include/linux/iopoll.h @@ -19,19 +19,19 @@ * @op: accessor function (takes @args as its arguments) * @val: Variable to read the value into * @cond: Break condition (usually involving @val) - * @sleep_us: Maximum time to sleep between reads in us (0 - * tight-loops). Should be less than ~20ms since usleep_range - * is used (see Documentation/timers/timers-howto.rst). + * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please + * read usleep_range() function description for details and + * limitations. * @timeout_us: Timeout in us, 0 means never timeout * @sleep_before_read: if it is true, sleep @sleep_us before read. * @args: arguments for @op poll * - * Returns 0 on success and -ETIMEDOUT upon a timeout. In either - * case, the last read value at @args is stored in @val. Must not - * be called from atomic context if sleep_us or timeout_us are used. - * * When available, you'll probably want to use one of the specialized * macros defined below rather than this macro directly. + * + * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either + * case, the last read value at @args is stored in @val. Must not + * be called from atomic context if sleep_us or timeout_us are used. */ #define read_poll_timeout(op, val, cond, sleep_us, timeout_us, \ sleep_before_read, args...) \ @@ -53,6 +53,7 @@ } \ if (__sleep_us) \ usleep_range((__sleep_us >> 2) + 1, __sleep_us); \ + cpu_relax(); \ } \ (cond) ? 0 : -ETIMEDOUT; \ }) @@ -63,38 +64,51 @@ * @op: accessor function (takes @args as its arguments) * @val: Variable to read the value into * @cond: Break condition (usually involving @val) - * @delay_us: Time to udelay between reads in us (0 tight-loops). Should - * be less than ~10us since udelay is used (see - * Documentation/timers/timers-howto.rst). + * @delay_us: Time to udelay between reads in us (0 tight-loops). Please + * read udelay() function description for details and + * limitations. * @timeout_us: Timeout in us, 0 means never timeout * @delay_before_read: if it is true, delay @delay_us before read. * @args: arguments for @op poll * - * Returns 0 on success and -ETIMEDOUT upon a timeout. In either - * case, the last read value at @args is stored in @val. + * This macro does not rely on timekeeping. Hence it is safe to call even when + * timekeeping is suspended, at the expense of an underestimation of wall clock + * time, which is rather minimal with a non-zero delay_us. * * When available, you'll probably want to use one of the specialized * macros defined below rather than this macro directly. + * + * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either + * case, the last read value at @args is stored in @val. */ #define read_poll_timeout_atomic(op, val, cond, delay_us, timeout_us, \ delay_before_read, args...) \ ({ \ u64 __timeout_us = (timeout_us); \ + s64 __left_ns = __timeout_us * NSEC_PER_USEC; \ unsigned long __delay_us = (delay_us); \ - ktime_t __timeout = ktime_add_us(ktime_get(), __timeout_us); \ - if (delay_before_read && __delay_us) \ + u64 __delay_ns = __delay_us * NSEC_PER_USEC; \ + if (delay_before_read && __delay_us) { \ udelay(__delay_us); \ + if (__timeout_us) \ + __left_ns -= __delay_ns; \ + } \ for (;;) { \ (val) = op(args); \ if (cond) \ break; \ - if (__timeout_us && \ - ktime_compare(ktime_get(), __timeout) > 0) { \ + if (__timeout_us && __left_ns < 0) { \ (val) = op(args); \ break; \ } \ - if (__delay_us) \ + if (__delay_us) { \ udelay(__delay_us); \ + if (__timeout_us) \ + __left_ns -= __delay_ns; \ + } \ + cpu_relax(); \ + if (__timeout_us) \ + __left_ns--; \ } \ (cond) ? 0 : -ETIMEDOUT; \ }) @@ -105,17 +119,17 @@ * @addr: Address to poll * @val: Variable to read the value into * @cond: Break condition (usually involving @val) - * @sleep_us: Maximum time to sleep between reads in us (0 - * tight-loops). Should be less than ~20ms since usleep_range - * is used (see Documentation/timers/timers-howto.rst). + * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please + * read usleep_range() function description for details and + * limitations. * @timeout_us: Timeout in us, 0 means never timeout * - * Returns 0 on success and -ETIMEDOUT upon a timeout. In either - * case, the last read value at @addr is stored in @val. Must not - * be called from atomic context if sleep_us or timeout_us are used. - * * When available, you'll probably want to use one of the specialized * macros defined below rather than this macro directly. + * + * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either + * case, the last read value at @addr is stored in @val. Must not + * be called from atomic context if sleep_us or timeout_us are used. */ #define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us) \ read_poll_timeout(op, val, cond, sleep_us, timeout_us, false, addr) @@ -126,16 +140,16 @@ * @addr: Address to poll * @val: Variable to read the value into * @cond: Break condition (usually involving @val) - * @delay_us: Time to udelay between reads in us (0 tight-loops). Should - * be less than ~10us since udelay is used (see - * Documentation/timers/timers-howto.rst). + * @delay_us: Time to udelay between reads in us (0 tight-loops). Please + * read udelay() function description for details and + * limitations. * @timeout_us: Timeout in us, 0 means never timeout * - * Returns 0 on success and -ETIMEDOUT upon a timeout. In either - * case, the last read value at @addr is stored in @val. - * * When available, you'll probably want to use one of the specialized * macros defined below rather than this macro directly. + * + * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either + * case, the last read value at @addr is stored in @val. */ #define readx_poll_timeout_atomic(op, addr, val, cond, delay_us, timeout_us) \ read_poll_timeout_atomic(op, val, cond, delay_us, timeout_us, false, addr) |