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[220.235.109.115]) by smtp.gmail.com with ESMTPSA id k10sm3225147pjs.31.2019.11.23.18.25.29 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sat, 23 Nov 2019 18:25:31 -0800 (PST) Date: Sun, 24 Nov 2019 10:25:26 +0800 From: Kent Gibson To: Bartosz Golaszewski Cc: "open list:GPIO SUBSYSTEM" , Bartosz Golaszewski Subject: Re: [PATCH v2] core: deprecate gpiod_needs_update() Message-ID: <20191124022526.GA9031@sol> References: <20191122103512.12173-1-brgl@bgdev.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-gpio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org On Sat, Nov 23, 2019 at 03:50:23PM +0100, Bartosz Golaszewski wrote: > pt., 22 lis 2019 o 11:35 Bartosz Golaszewski napisał(a): > > > > From: Bartosz Golaszewski > > > > This function and the logic behind have been introduced in an early > > version of libgpiod for reasons that have been long forgotten. > > > > When updating the line info after a line request fails, just propagate > > the error out of the request function instead of setting the internal > > needs_update variable. Drop the entire logic behind gpiod_needs_update(), > > make this routine always return false and mark it as deprecated in the > > header. > > > > Suggested-by: Kent Gibson > > Signed-off-by: Bartosz Golaszewski > > --- > > v1 -> v2: > > - made the documentation of gpiod_line_update() clearer > > > > include/gpiod.h | 39 +++++++++++++++++---------------------- > > lib/core.c | 30 ++++++++++++++---------------- > > tests/tests-line.c | 2 -- > > 3 files changed, 31 insertions(+), 40 deletions(-) > > > > diff --git a/include/gpiod.h b/include/gpiod.h > > index 6dfa18a..3fc1c0c 100644 > > --- a/include/gpiod.h > > +++ b/include/gpiod.h > > @@ -725,37 +725,32 @@ bool gpiod_line_is_open_source(struct gpiod_line *line) GPIOD_API; > > /** > > * @brief Re-read the line info. > > * @param line GPIO line object. > > - * @return 0 is the operation succeeds. In case of an error this routine > > + * @return 0 if the operation succeeds. In case of an error this routine > > * returns -1 and sets the last error number. > > * > > * The line info is initially retrieved from the kernel by > > - * gpiod_chip_get_line(). Users can use this line to manually re-read the line > > - * info. > > + * gpiod_chip_get_line() and is later re-read after every successful request. > > + * Users can use this function to manually re-read the line info when needed. > > + * > > + * We currently have no mechanism provided by the kernel for keeping the line > > + * info synchronized and for the sake of speed and simplicity of this low-level > > + * library we don't want to re-read the line info automatically everytime > > + * a property is retrieved. Any daemon using this library must track the state > > + * of lines on its own and call this routine if needed. > > + * > > + * The state of requested lines is kept synchronized (or rather cannot be > > + * changed by external agents while the ownership of the line is taken) so > > + * there's no need to call this function in that case. > > */ > > int gpiod_line_update(struct gpiod_line *line) GPIOD_API; > > > > /** > > * @brief Check if the line info needs to be updated. > > * @param line GPIO line object. > > - * @return Returns false if the line is up-to-date. True otherwise. > > - * > > - * The line is updated by calling gpiod_line_update() from within > > - * gpiod_chip_get_line() and on every line request/release. However: an error > > - * returned from gpiod_line_update() only breaks the execution of the former. > > - * The request/release routines only set the internal needs_update flag to true > > - * and continue their execution. This routine allows to check if a line info > > - * update failed at some point and we should call gpiod_line_update() > > - * explicitly. > > - * > > - * This routine will not indicate any potential changes introduced by external > > - * actors (such as a different process requesting the line). We currently have > > - * no mechanism provided by the kernel for that and for the sake of speed and > > - * simplicity of this low-level library we don't want to re-read the line info > > - * automatically everytime a property is retrieved. Any daemon using this > > - * library must track the state of lines on its own and call > > - * ::gpiod_line_update if needed. > > - */ > > -bool gpiod_line_needs_update(struct gpiod_line *line) GPIOD_API; > > + * @return Deprecated and no longer functional - always returns false. > > + */ > > +bool > > +gpiod_line_needs_update(struct gpiod_line *line) GPIOD_API GPIOD_DEPRECATED; > > > > /** > > * @} > > diff --git a/lib/core.c b/lib/core.c > > index d79e52e..a21918c 100644 > > --- a/lib/core.c > > +++ b/lib/core.c > > @@ -41,7 +41,6 @@ struct gpiod_line { > > bool open_drain; > > > > int state; > > - bool needs_update; > > > > struct gpiod_chip *chip; > > struct line_fd_handle *fd_handle; > > @@ -320,15 +319,6 @@ static int line_get_fd(struct gpiod_line *line) > > return line->fd_handle->fd; > > } > > > > -static void line_maybe_update(struct gpiod_line *line) > > -{ > > - int rv; > > - > > - rv = gpiod_line_update(line); > > - if (rv < 0) > > - line->needs_update = true; > > -} > > - > > struct gpiod_chip *gpiod_line_get_chip(struct gpiod_line *line) > > { > > return line->chip; > > @@ -374,9 +364,9 @@ bool gpiod_line_is_open_source(struct gpiod_line *line) > > return line->open_source; > > } > > > > -bool gpiod_line_needs_update(struct gpiod_line *line) > > +bool gpiod_line_needs_update(struct gpiod_line *line GPIOD_UNUSED) > > { > > - return line->needs_update; > > + return false; > > } > > > > int gpiod_line_update(struct gpiod_line *line) > > @@ -405,8 +395,6 @@ int gpiod_line_update(struct gpiod_line *line) > > strncpy(line->name, info.name, sizeof(line->name)); > > strncpy(line->consumer, info.consumer, sizeof(line->consumer)); > > > > - line->needs_update = false; > > - > > return 0; > > } > > > > @@ -537,7 +525,12 @@ static int line_request_values(struct gpiod_line_bulk *bulk, > > gpiod_line_bulk_foreach_line(bulk, line, lineptr) { > > line->state = LINE_REQUESTED_VALUES; > > line_set_fd(line, line_fd); > > - line_maybe_update(line); > > + > > + rv = gpiod_line_update(line); > > + if (rv) { > > + gpiod_line_release_bulk(bulk); > > + return rv; > > + } > > } > > > > return 0; > > @@ -577,7 +570,12 @@ static int line_request_event_single(struct gpiod_line *line, > > > > line->state = LINE_REQUESTED_EVENTS; > > line_set_fd(line, line_fd); > > - line_maybe_update(line); > > + > > + rv = gpiod_line_update(line); > > + if (rv) { > > + gpiod_line_release(line); > > + return rv; > > + } > > > > return 0; > > } > > diff --git a/tests/tests-line.c b/tests/tests-line.c > > index 8411132..205c622 100644 > > --- a/tests/tests-line.c > > +++ b/tests/tests-line.c > > @@ -78,7 +78,6 @@ GPIOD_TEST_CASE(consumer, 0, { 8 }) > > > > ret = gpiod_line_request_input(line, GPIOD_TEST_CONSUMER); > > g_assert_cmpint(ret, ==, 0); > > - g_assert_false(gpiod_line_needs_update(line)); > > g_assert_cmpstr(gpiod_line_consumer(line), ==, GPIOD_TEST_CONSUMER); > > } > > > > @@ -101,7 +100,6 @@ GPIOD_TEST_CASE(consumer_long_string, 0, { 8 }) > > ret = gpiod_line_request_input(line, > > "consumer string over 32 characters long"); > > g_assert_cmpint(ret, ==, 0); > > - g_assert_false(gpiod_line_needs_update(line)); > > g_assert_cmpstr(gpiod_line_consumer(line), ==, > > "consumer string over 32 charact"); > > g_assert_cmpuint(strlen(gpiod_line_consumer(line)), ==, 31); > > -- > > 2.23.0 > > > > Seems I missed the [libgpiod] tag. Anyway - patch applied. > > Kent: hopefully it won't be too much work for you to rebase on top of > current master. Otherwise I can probably fix the patches up myself. > No problem at all. I've rebased my pre-v3 on the current master@296441, and made the corresponding changes to set_config and set_flags. Those changes are also committed to my development branch on github, if you want a preview. Do you want to review the v2 or should I submit the v3 as is? Cheers, Kent.