Re: [PATCH v2 2/2] drm: zynqmp_dp: Use scope-based mutex helpers
From: Laurent Pinchart
Date: Fri Feb 07 2025 - 11:45:05 EST
Hi Sean,
Thank you for the patch.
On Fri, Feb 07, 2025 at 11:25:28AM -0500, Sean Anderson wrote:
> Convert most mutex_(un)lock calls to use (scoped_)guard instead. This
> generally reduces line count and prevents bugs like forgetting to unlock
> the mutex. I've left traditional calls in a few places where scoped
> helpers would be more verbose. This mostly happens where
> debugfs_file_put needs to be called regardless. I looked into defining a
> CLASS for debugfs_file, but it seems like more effort than it's worth
> since debugfs_file_get can fail.
>
> Signed-off-by: Sean Anderson <sean.anderson@xxxxxxxxx>
> ---
>
> Changes in v2:
> - Convert some conditional return statements to returns of ternary
> expressions.
> - Remove unnecessary whitespace change
>
> drivers/gpu/drm/xlnx/zynqmp_dp.c | 147 +++++++++++--------------------
> 1 file changed, 50 insertions(+), 97 deletions(-)
>
> diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
> index 189a08cdc73c..63842f657836 100644
> --- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
> +++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
> @@ -1534,10 +1534,10 @@ zynqmp_dp_bridge_mode_valid(struct drm_bridge *bridge,
> }
>
> /* Check with link rate and lane count */
> - mutex_lock(&dp->lock);
> - rate = zynqmp_dp_max_rate(dp->link_config.max_rate,
> - dp->link_config.max_lanes, dp->config.bpp);
> - mutex_unlock(&dp->lock);
> + scoped_guard(mutex, &dp->lock)
> + rate = zynqmp_dp_max_rate(dp->link_config.max_rate,
> + dp->link_config.max_lanes,
> + dp->config.bpp);
Could we use curly braces even for single-statement scopes ?
scoped_guard(mutex, &dp->lock) {
rate = zynqmp_dp_max_rate(dp->link_config.max_rate,
dp->link_config.max_lanes,
dp->config.bpp);
}
I think this would make the scope clearer.
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> if (mode->clock > rate) {
> dev_dbg(dp->dev, "filtered mode %s for high pixel rate\n",
> mode->name);
> @@ -1722,13 +1722,9 @@ static enum drm_connector_status __zynqmp_dp_bridge_detect(struct zynqmp_dp *dp)
> static enum drm_connector_status zynqmp_dp_bridge_detect(struct drm_bridge *bridge)
> {
> struct zynqmp_dp *dp = bridge_to_dp(bridge);
> - enum drm_connector_status ret;
>
> - mutex_lock(&dp->lock);
> - ret = __zynqmp_dp_bridge_detect(dp);
> - mutex_unlock(&dp->lock);
> -
> - return ret;
> + guard(mutex)(&dp->lock);
> + return __zynqmp_dp_bridge_detect(dp);
> }
>
> static const struct drm_edid *zynqmp_dp_bridge_edid_read(struct drm_bridge *bridge,
> @@ -1881,10 +1877,9 @@ static ssize_t zynqmp_dp_pattern_read(struct file *file, char __user *user_buf,
> if (unlikely(ret))
> return ret;
>
> - mutex_lock(&dp->lock);
> - ret = snprintf(buf, sizeof(buf), "%s\n",
> - test_pattern_str[dp->test.pattern]);
> - mutex_unlock(&dp->lock);
> + scoped_guard(mutex, &dp->lock)
> + ret = snprintf(buf, sizeof(buf), "%s\n",
> + test_pattern_str[dp->test.pattern]);
>
> debugfs_file_put(dentry);
> return simple_read_from_buffer(user_buf, count, ppos, buf, ret);
> @@ -1939,24 +1934,18 @@ static int zynqmp_dp_enhanced_get(void *data, u64 *val)
> {
> struct zynqmp_dp *dp = data;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> *val = dp->test.enhanced;
> - mutex_unlock(&dp->lock);
> return 0;
> }
>
> static int zynqmp_dp_enhanced_set(void *data, u64 val)
> {
> struct zynqmp_dp *dp = data;
> - int ret = 0;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> dp->test.enhanced = val;
> - if (dp->test.active)
> - ret = zynqmp_dp_test_setup(dp);
> - mutex_unlock(&dp->lock);
> -
> - return ret;
> + return dp->test.active ? zynqmp_dp_test_setup(dp) : 0;
> }
>
> DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_enhanced, zynqmp_dp_enhanced_get,
> @@ -1966,24 +1955,19 @@ static int zynqmp_dp_downspread_get(void *data, u64 *val)
> {
> struct zynqmp_dp *dp = data;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> *val = dp->test.downspread;
> - mutex_unlock(&dp->lock);
> return 0;
> }
>
> static int zynqmp_dp_downspread_set(void *data, u64 val)
> {
> struct zynqmp_dp *dp = data;
> - int ret = 0;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> dp->test.downspread = val;
> - if (dp->test.active)
> - ret = zynqmp_dp_test_setup(dp);
> - mutex_unlock(&dp->lock);
>
> - return ret;
> + return dp->test.active ? zynqmp_dp_test_setup(dp) : 0;
> }
>
> DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_downspread, zynqmp_dp_downspread_get,
> @@ -1993,33 +1977,32 @@ static int zynqmp_dp_active_get(void *data, u64 *val)
> {
> struct zynqmp_dp *dp = data;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> *val = dp->test.active;
> - mutex_unlock(&dp->lock);
> return 0;
> }
>
> static int zynqmp_dp_active_set(void *data, u64 val)
> {
> struct zynqmp_dp *dp = data;
> - int ret = 0;
> + int ret;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> if (val) {
> if (val < 2) {
> ret = zynqmp_dp_test_setup(dp);
> if (ret)
> - goto out;
> + return ret;
> }
>
> ret = zynqmp_dp_set_test_pattern(dp, dp->test.pattern,
> dp->test.custom);
> if (ret)
> - goto out;
> + return ret;
>
> ret = zynqmp_dp_update_vs_emph(dp, dp->test.train_set);
> if (ret)
> - goto out;
> + return ret;
>
> dp->test.active = true;
> } else {
> @@ -2032,10 +2015,8 @@ static int zynqmp_dp_active_set(void *data, u64 val)
> err);
> zynqmp_dp_train_loop(dp);
> }
> -out:
> - mutex_unlock(&dp->lock);
>
> - return ret;
> + return 0;
> }
>
> DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_active, zynqmp_dp_active_get,
> @@ -2102,9 +2083,8 @@ static int zynqmp_dp_swing_get(void *data, u64 *val)
> struct zynqmp_dp_train_set_priv *priv = data;
> struct zynqmp_dp *dp = priv->dp;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> *val = dp->test.train_set[priv->lane] & DP_TRAIN_VOLTAGE_SWING_MASK;
> - mutex_unlock(&dp->lock);
> return 0;
> }
>
> @@ -2113,12 +2093,11 @@ static int zynqmp_dp_swing_set(void *data, u64 val)
> struct zynqmp_dp_train_set_priv *priv = data;
> struct zynqmp_dp *dp = priv->dp;
> u8 *train_set = &dp->test.train_set[priv->lane];
> - int ret = 0;
>
> if (val > 3)
> return -EINVAL;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> *train_set &= ~(DP_TRAIN_MAX_SWING_REACHED |
> DP_TRAIN_VOLTAGE_SWING_MASK);
> *train_set |= val;
> @@ -2126,10 +2105,9 @@ static int zynqmp_dp_swing_set(void *data, u64 val)
> *train_set |= DP_TRAIN_MAX_SWING_REACHED;
>
> if (dp->test.active)
> - ret = zynqmp_dp_update_vs_emph(dp, dp->test.train_set);
> - mutex_unlock(&dp->lock);
> + return zynqmp_dp_update_vs_emph(dp, dp->test.train_set);
>
> - return ret;
> + return 0;
> }
>
> DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_swing, zynqmp_dp_swing_get,
> @@ -2140,10 +2118,9 @@ static int zynqmp_dp_preemphasis_get(void *data, u64 *val)
> struct zynqmp_dp_train_set_priv *priv = data;
> struct zynqmp_dp *dp = priv->dp;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> *val = FIELD_GET(DP_TRAIN_PRE_EMPHASIS_MASK,
> dp->test.train_set[priv->lane]);
> - mutex_unlock(&dp->lock);
> return 0;
> }
>
> @@ -2152,12 +2129,11 @@ static int zynqmp_dp_preemphasis_set(void *data, u64 val)
> struct zynqmp_dp_train_set_priv *priv = data;
> struct zynqmp_dp *dp = priv->dp;
> u8 *train_set = &dp->test.train_set[priv->lane];
> - int ret = 0;
>
> if (val > 2)
> return -EINVAL;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> *train_set &= ~(DP_TRAIN_MAX_PRE_EMPHASIS_REACHED |
> DP_TRAIN_PRE_EMPHASIS_MASK);
> *train_set |= val;
> @@ -2165,10 +2141,9 @@ static int zynqmp_dp_preemphasis_set(void *data, u64 val)
> *train_set |= DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;
>
> if (dp->test.active)
> - ret = zynqmp_dp_update_vs_emph(dp, dp->test.train_set);
> - mutex_unlock(&dp->lock);
> + return zynqmp_dp_update_vs_emph(dp, dp->test.train_set);
>
> - return ret;
> + return 0;
> }
>
> DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_preemphasis, zynqmp_dp_preemphasis_get,
> @@ -2178,31 +2153,24 @@ static int zynqmp_dp_lanes_get(void *data, u64 *val)
> {
> struct zynqmp_dp *dp = data;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> *val = dp->test.link_cnt;
> - mutex_unlock(&dp->lock);
> return 0;
> }
>
> static int zynqmp_dp_lanes_set(void *data, u64 val)
> {
> struct zynqmp_dp *dp = data;
> - int ret = 0;
>
> if (val > ZYNQMP_DP_MAX_LANES)
> return -EINVAL;
>
> - mutex_lock(&dp->lock);
> - if (val > dp->num_lanes) {
> - ret = -EINVAL;
> - } else {
> - dp->test.link_cnt = val;
> - if (dp->test.active)
> - ret = zynqmp_dp_test_setup(dp);
> - }
> - mutex_unlock(&dp->lock);
> + guard(mutex)(&dp->lock);
> + if (val > dp->num_lanes)
> + return -EINVAL;
>
> - return ret;
> + dp->test.link_cnt = val;
> + return dp->test.active ? zynqmp_dp_test_setup(dp) : 0;
> }
>
> DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_lanes, zynqmp_dp_lanes_get,
> @@ -2212,9 +2180,8 @@ static int zynqmp_dp_rate_get(void *data, u64 *val)
> {
> struct zynqmp_dp *dp = data;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> *val = drm_dp_bw_code_to_link_rate(dp->test.bw_code) * 10000ULL;
> - mutex_unlock(&dp->lock);
> return 0;
> }
>
> @@ -2222,7 +2189,6 @@ static int zynqmp_dp_rate_set(void *data, u64 val)
> {
> struct zynqmp_dp *dp = data;
> int link_rate;
> - int ret = 0;
> u8 bw_code;
>
> if (do_div(val, 10000))
> @@ -2237,13 +2203,9 @@ static int zynqmp_dp_rate_set(void *data, u64 val)
> bw_code != DP_LINK_BW_5_4)
> return -EINVAL;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> dp->test.bw_code = bw_code;
> - if (dp->test.active)
> - ret = zynqmp_dp_test_setup(dp);
> - mutex_unlock(&dp->lock);
> -
> - return ret;
> + return dp->test.active ? zynqmp_dp_test_setup(dp) : 0;
> }
>
> DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_rate, zynqmp_dp_rate_get,
> @@ -2253,9 +2215,8 @@ static int zynqmp_dp_ignore_aux_errors_get(void *data, u64 *val)
> {
> struct zynqmp_dp *dp = data;
>
> - mutex_lock(&dp->aux.hw_mutex);
> + guard(mutex)(&dp->lock);
> *val = dp->ignore_aux_errors;
> - mutex_unlock(&dp->aux.hw_mutex);
> return 0;
> }
>
> @@ -2266,9 +2227,8 @@ static int zynqmp_dp_ignore_aux_errors_set(void *data, u64 val)
> if (val != !!val)
> return -EINVAL;
>
> - mutex_lock(&dp->aux.hw_mutex);
> + guard(mutex)(&dp->lock);
> dp->ignore_aux_errors = val;
> - mutex_unlock(&dp->aux.hw_mutex);
> return 0;
> }
>
> @@ -2280,9 +2240,8 @@ static int zynqmp_dp_ignore_hpd_get(void *data, u64 *val)
> {
> struct zynqmp_dp *dp = data;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> *val = dp->ignore_hpd;
> - mutex_unlock(&dp->lock);
> return 0;
> }
>
> @@ -2293,9 +2252,8 @@ static int zynqmp_dp_ignore_hpd_set(void *data, u64 val)
> if (val != !!val)
> return -EINVAL;
>
> - mutex_lock(&dp->lock);
> + guard(mutex)(&dp->lock);
> dp->ignore_hpd = val;
> - mutex_unlock(&dp->lock);
> return 0;
> }
>
> @@ -2391,14 +2349,12 @@ static void zynqmp_dp_hpd_work_func(struct work_struct *work)
> struct zynqmp_dp *dp = container_of(work, struct zynqmp_dp, hpd_work);
> enum drm_connector_status status;
>
> - mutex_lock(&dp->lock);
> - if (dp->ignore_hpd) {
> - mutex_unlock(&dp->lock);
> - return;
> - }
> + scoped_guard(mutex, &dp->lock) {
> + if (dp->ignore_hpd)
> + return;
>
> - status = __zynqmp_dp_bridge_detect(dp);
> - mutex_unlock(&dp->lock);
> + status = __zynqmp_dp_bridge_detect(dp);
> + }
>
> drm_bridge_hpd_notify(&dp->bridge, status);
> }
> @@ -2410,11 +2366,9 @@ static void zynqmp_dp_hpd_irq_work_func(struct work_struct *work)
> u8 status[DP_LINK_STATUS_SIZE + 2];
> int err;
>
> - mutex_lock(&dp->lock);
> - if (dp->ignore_hpd) {
> - mutex_unlock(&dp->lock);
> + guard(mutex)(&dp->lock);
> + if (dp->ignore_hpd)
> return;
> - }
>
> err = drm_dp_dpcd_read(&dp->aux, DP_SINK_COUNT, status,
> DP_LINK_STATUS_SIZE + 2);
> @@ -2428,7 +2382,6 @@ static void zynqmp_dp_hpd_irq_work_func(struct work_struct *work)
> zynqmp_dp_train_loop(dp);
> }
> }
> - mutex_unlock(&dp->lock);
> }
>
> static irqreturn_t zynqmp_dp_irq_handler(int irq, void *data)
--
Regards,
Laurent Pinchart