From: Richard Henderson <richard.henderson@linaro.org>
To: Peter Maydell <peter.maydell@linaro.org>,
qemu-arm@nongnu.org, qemu-devel@nongnu.org
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>
Subject: Re: [PATCH v2 02/21] ptimer: Provide new transaction-based API
Date: Tue, 8 Oct 2019 21:44:17 -0400 [thread overview]
Message-ID: <3a24d643-20ba-7328-f643-5a7d6be20ae5@linaro.org> (raw)
In-Reply-To: <20191008171740.9679-3-peter.maydell@linaro.org>
On 10/8/19 1:17 PM, Peter Maydell wrote:
> Provide the new transaction-based API. If a ptimer is created
> using ptimer_init() rather than ptimer_init_with_bh(), then
> instead of providing a QEMUBH, it provides a pointer to the
> callback function directly, and has opted into the transaction
> API. All calls to functions which modify ptimer state:
> - ptimer_set_period()
> - ptimer_set_freq()
> - ptimer_set_limit()
> - ptimer_set_count()
> - ptimer_run()
> - ptimer_stop()
> must be between matched calls to ptimer_transaction_begin()
> and ptimer_transaction_commit(). When ptimer_transaction_commit()
> is called it will evaluate the state of the timer after all the
> changes in the transaction, and call the callback if necessary.
>
> In the old API the individual update functions generally would
> call ptimer_trigger() immediately, which would schedule the QEMUBH.
> In the new API the update functions will instead defer the
> "set s->next_event and call ptimer_reload()" work to
> ptimer_transaction_commit().
>
> Because ptimer_trigger() can now immediately call into the
> device code which may then call other ptimer functions that
> update ptimer_state fields, we must be more careful in
> ptimer_reload() not to cache fields from ptimer_state across
> the ptimer_trigger() call. (This was harmless with the QEMUBH
> mechanism as the BH would not be invoked until much later.)
>
> We use assertions to check that:
> * the functions modifying ptimer state are not called outside
> a transaction block
> * ptimer_transaction_begin() and _commit() calls are paired
> * the transaction API is not used with a QEMUBH ptimer
>
> There is some slight repetition of code:
> * most of the set functions have similar looking "if s->bh
> call ptimer_reload, otherwise set s->need_reload" code
> * ptimer_init() and ptimer_init_with_bh() have similar code
> We deliberately don't try to avoid this repetition, because
> it will all be deleted when the QEMUBH version of the API
> is removed.
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
r~
next prev parent reply other threads:[~2019-10-09 1:45 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-08 17:17 [PATCH v2 00/21] transaction-based ptimer API Peter Maydell
2019-10-08 17:17 ` [PATCH v2 01/21] ptimer: Rename ptimer_init() to ptimer_init_with_bh() Peter Maydell
2019-10-08 17:17 ` [PATCH v2 02/21] ptimer: Provide new transaction-based API Peter Maydell
2019-10-09 1:44 ` Richard Henderson [this message]
2019-10-08 17:17 ` [PATCH v2 03/21] tests/ptimer-test: Switch to transaction-based ptimer API Peter Maydell
2019-10-09 1:46 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 04/21] hw/timer/arm_timer.c: " Peter Maydell
2019-10-09 1:47 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 05/21] hw/arm/musicpal.c: " Peter Maydell
2019-10-09 1:48 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 06/21] hw/timer/allwinner-a10-pit.c: " Peter Maydell
2019-10-09 1:49 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 07/21] hw/timer/arm_mptimer.c: " Peter Maydell
2019-10-09 1:50 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 08/21] hw/timer/cmsdk-apb-dualtimer.c: " Peter Maydell
2019-10-09 1:51 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 09/21] hw/timer/cmsdk-apb-timer.c: " Peter Maydell
2019-10-09 1:52 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 10/21] hw/timer/digic-timer.c: " Peter Maydell
2019-10-09 1:53 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 11/21] hw/timer/exynos4210_mct.c: Switch GFRC " Peter Maydell
2019-10-09 1:56 ` Richard Henderson
2019-10-09 1:58 ` Richard Henderson
2019-10-09 13:49 ` Peter Maydell
2019-10-09 1:58 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 12/21] hw/timer/exynos4210_mct.c: Switch LFRC " Peter Maydell
2019-10-09 1:58 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 13/21] hw/timer/exynos4210_mct.c: Switch ltick " Peter Maydell
2019-10-09 1:59 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 14/21] hw/timer/exynos4210_pwm.c: Switch " Peter Maydell
2019-10-09 2:00 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 15/21] hw/timer/exynos4210_rtc.c: Switch 1Hz ptimer to transaction-based API Peter Maydell
2019-10-09 2:01 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 16/21] hw/timer/exynos4210_rtc.c: Switch main " Peter Maydell
2019-10-09 2:02 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 17/21] hw/timer/imx_epit.c: Switch to transaction-based ptimer API Peter Maydell
2019-10-09 2:03 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 18/21] hw/timer/imx_gpt.c: " Peter Maydell
2019-10-09 2:04 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 19/21] hw/timer/mss-timerc: " Peter Maydell
2019-10-09 2:05 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 20/21] hw/watchdog/cmsdk-apb-watchdog.c: " Peter Maydell
2019-10-09 2:06 ` Richard Henderson
2019-10-08 17:17 ` [PATCH v2 21/21] hw/net/lan9118.c: " Peter Maydell
2019-10-09 2:07 ` Richard Henderson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=3a24d643-20ba-7328-f643-5a7d6be20ae5@linaro.org \
--to=richard.henderson@linaro.org \
--cc=pbonzini@redhat.com \
--cc=peter.maydell@linaro.org \
--cc=philmd@redhat.com \
--cc=qemu-arm@nongnu.org \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.