When cdev_add is called after device_add has been called there is no way for the userspace to know about the addition of a cdev as cdev_add itself doesn't trigger a uevent notification, or for the kernel to know about the change to devt. This results in two problems: - mknod is never called for the cdev and hence no cdev appears on devtmpfs. - sysfs links to the new cdev are not established.

The cdev needs to be added and devt assigned before device_add() is called in order for the relevant sysfs and devtmpfs entries to be created and the uevent to be properly populated.

Signed-off-by: Siddharth Gupta sidgup@codeaurora.org Reviewed-by: Bjorn Andersson bjorn.andersson@linaro.org --- drivers/remoteproc/remoteproc_core.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c index 6348aaa..9ad8c5f 100644 --- a/drivers/remoteproc/remoteproc_core.c +++ b/drivers/remoteproc/remoteproc_core.c @@ -2333,6 +2333,11 @@ int rproc_add(struct rproc *rproc) struct device *dev = &rproc->dev; int ret;

+ /* add char device for this remoteproc */ + ret = rproc_char_device_add(rproc); + if (ret < 0) + return ret; + ret = device_add(dev); if (ret < 0) return ret; @@ -2346,11 +2351,6 @@ int rproc_add(struct rproc *rproc) /* create debugfs entries */ rproc_create_debug_dir(rproc);

- /* add char device for this remoteproc */ - ret = rproc_char_device_add(rproc); - if (ret < 0) - return ret; - /* if rproc is marked always-on, request it to boot */ if (rproc->auto_boot) { ret = rproc_trigger_auto_boot(rproc);

The rproc_char_device_remove() call currently unmaps the cdev region instead of simply deleting the cdev that was added as a part of the rproc_char_device_add() call. This change fixes that behaviour, and also fixes the order in which device_del() and cdev_del() need to be called.

Signed-off-by: Siddharth Gupta sidgup@codeaurora.org --- 0000-cover-letter.patch.backup | 26 ++++++++++++++++++++++++++ drivers/remoteproc/remoteproc_cdev.c | 2 +- drivers/remoteproc/remoteproc_core.c | 2 +- 3 files changed, 28 insertions(+), 2 deletions(-) create mode 100644 0000-cover-letter.patch.backup

diff --git a/0000-cover-letter.patch.backup b/0000-cover-letter.patch.backup new file mode 100644 index 0000000..837bcdb --- /dev/null +++ b/0000-cover-letter.patch.backup @@ -0,0 +1,26 @@ +From 78fcb27d574d2f7b06e37b77b257f98858a88d9d Mon Sep 17 00:00:00 2001 +From: Siddharth Gupta sidgup@codeaurora.org +Date: Mon, 17 May 2021 13:33:25 -0700 +Subject: [PATCH 0/3] remoteproc: core: Fixes for rproc cdev and add +To: bjorn.andersson@linaro.org,ohad@wizery.com,linux-remoteproc@vger.kernel.org +Cc: linux-kernel@vger.kernel.org,linux-arm-msm@vger.kernel.org,linux-arm-kernel@lists.infradead.org,psodagud@codeaurora.org,stable@vger.kernel.org + +This patch series contains stability fixes and error handling for remoteproc. + +The changes included in this series do the following: +Patch 1: Fixes the creation of the rproc character device. +Patch 2: Validates rproc as the first step of rproc_add(). +Patch 3: Adds error handling in rproc_add(). + +Siddharth Gupta (3): + remoteproc: core: Move cdev add before device add + remoteproc: core: Move validate before device add + remoteproc: core: Cleanup device in case of failure + + drivers/remoteproc/remoteproc_core.c | 25 +++++++++++++++++-------- + 1 file changed, 17 insertions(+), 8 deletions(-) + +-- +Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, +a Linux Foundation Collaborative Project + diff --git a/drivers/remoteproc/remoteproc_cdev.c b/drivers/remoteproc/remoteproc_cdev.c index 0b8a84c..4ad98b0 100644 --- a/drivers/remoteproc/remoteproc_cdev.c +++ b/drivers/remoteproc/remoteproc_cdev.c @@ -124,7 +124,7 @@ int rproc_char_device_add(struct rproc *rproc)

void rproc_char_device_remove(struct rproc *rproc) { - __unregister_chrdev(MAJOR(rproc->dev.devt), rproc->index, 1, "remoteproc"); + cdev_del(&rproc->cdev); }

void __init rproc_init_cdev(void) diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c index b65fce3..b874280 100644 --- a/drivers/remoteproc/remoteproc_core.c +++ b/drivers/remoteproc/remoteproc_core.c @@ -2619,7 +2619,6 @@ int rproc_del(struct rproc *rproc) mutex_unlock(&rproc->lock);

rproc_delete_debug_dir(rproc); - rproc_char_device_remove(rproc);

/* the rproc is downref'ed as soon as it's removed from the klist */ mutex_lock(&rproc_list_mutex); @@ -2630,6 +2629,7 @@ int rproc_del(struct rproc *rproc) synchronize_rcu();

device_del(&rproc->dev); + rproc_char_device_remove(rproc);

return 0; }