| Message ID | 20241217-syscon-fixes-v2-1-4f56d750541d@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mfd: syscon: Cleanup, fix race condition and remove platform driver | expand |
On 12/17/2024, Rob Herring (Arm) wrote: > It is possible for multiple, simultaneous callers calling > device_node_get_regmap() with the same node to fail to find an entry in > the syscon_list. There is a period of time while the first caller is > calling of_syscon_register() that subsequent callers also fail to find > an entry in the syscon_list and then call of_syscon_register() a second > time. > > Fix this by keeping the lock held until after of_syscon_register() > completes and adds the node to syscon_list. Convert the spinlock to a > mutex as many of the functions called in of_syscon_register() such as > kzalloc() and of_clk_get() may sleep. > > Fixes: bdb0066df96e ("mfd: syscon: Decouple syscon interface from platform devices") > Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> > Tested-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> > Signed-off-by: Rob Herring (Arm) <robh@kernel.org> I verified this works on my Pixel 6. Thanks! Tested-by: Will McVicker <willmcvicker@google.com> Thanks, Will
> -----Original Message----- > From: Rob Herring (Arm) <robh@kernel.org> > Sent: Tuesday, December 17, 2024 11:42 PM > To: Lee Jones <lee@kernel.org>; Arnd Bergmann <arnd@arndb.de>; Pankaj > Dubey <pankaj.dubey@samsung.com>; Heiko Stuebner <heiko@sntech.de>; > Liviu Dudau <liviu.dudau@arm.com>; Sudeep Holla <sudeep.holla@arm.com>; > Lorenzo Pieralisi <lpieralisi@kernel.org> > Cc: Peter Griffin <peter.griffin@linaro.org>; Will McVicker > <willmcvicker@google.com>; John Madieu <john.madieu.xa@bp.renesas.com>; > Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>; linux- > kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org > Subject: [PATCH v2 1/3] mfd: syscon: Fix race in device_node_get_regmap() > > It is possible for multiple, simultaneous callers calling > device_node_get_regmap() with the same node to fail to find an entry in the > syscon_list. There is a period of time while the first caller is calling > of_syscon_register() that subsequent callers also fail to find an entry in the > syscon_list and then call of_syscon_register() a second time. > > Fix this by keeping the lock held until after of_syscon_register() completes and > adds the node to syscon_list. Convert the spinlock to a mutex as many of the > functions called in of_syscon_register() such as > kzalloc() and of_clk_get() may sleep. > > Fixes: bdb0066df96e ("mfd: syscon: Decouple syscon interface from platform > devices") > Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> > Tested-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> > Signed-off-by: Rob Herring (Arm) <robh@kernel.org> > --- Tested on arm64: Tesla FSD Tested-by: Pankaj Dubey <pankaj.dubey@samsung.com> Thanks. Pankaj Dubey
> -----Original Message----- > From: Rob Herring (Arm) <robh@kernel.org> > Sent: Tuesday, December 17, 2024 11:42 PM > To: Lee Jones <lee@kernel.org>; Arnd Bergmann <arnd@arndb.de>; Pankaj > Dubey <pankaj.dubey@samsung.com>; Heiko Stuebner <heiko@sntech.de>; > Liviu Dudau <liviu.dudau@arm.com>; Sudeep Holla <sudeep.holla@arm.com>; > Lorenzo Pieralisi <lpieralisi@kernel.org> > Cc: Peter Griffin <peter.griffin@linaro.org>; Will McVicker > <willmcvicker@google.com>; John Madieu <john.madieu.xa@bp.renesas.com>; > Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>; linux- > kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org > Subject: [PATCH v2 1/3] mfd: syscon: Fix race in device_node_get_regmap() > > It is possible for multiple, simultaneous callers calling > device_node_get_regmap() with the same node to fail to find an entry in the > syscon_list. There is a period of time while the first caller is calling > of_syscon_register() that subsequent callers also fail to find an entry in the > syscon_list and then call of_syscon_register() a second time. > > Fix this by keeping the lock held until after of_syscon_register() completes and > adds the node to syscon_list. Convert the spinlock to a mutex as many of the > functions called in of_syscon_register() such as > kzalloc() and of_clk_get() may sleep. > > Fixes: bdb0066df96e ("mfd: syscon: Decouple syscon interface from platform > devices") > Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> > Tested-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> > Signed-off-by: Rob Herring (Arm) <robh@kernel.org> > --- Reviewed-by: Pankaj Dubey <pankaj.dubey@samsung.com>
diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c index 3e1d699ba9340f8135dfdeae6feca474980cc48d..72f20de9652da2d7bad12e4bc2c43ac0c9a97f76 100644 --- a/drivers/mfd/syscon.c +++ b/drivers/mfd/syscon.c @@ -15,6 +15,7 @@ #include <linux/io.h> #include <linux/init.h> #include <linux/list.h> +#include <linux/mutex.h> #include <linux/of.h> #include <linux/of_address.h> #include <linux/of_platform.h> @@ -27,7 +28,7 @@ static struct platform_driver syscon_driver; -static DEFINE_SPINLOCK(syscon_list_slock); +static DEFINE_MUTEX(syscon_list_lock); static LIST_HEAD(syscon_list); struct syscon { @@ -54,6 +55,8 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_res) struct resource res; struct reset_control *reset; + WARN_ON(!mutex_is_locked(&syscon_list_lock)); + struct syscon *syscon __free(kfree) = kzalloc(sizeof(*syscon), GFP_KERNEL); if (!syscon) return ERR_PTR(-ENOMEM); @@ -146,9 +149,7 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_res) syscon->regmap = regmap; syscon->np = np; - spin_lock(&syscon_list_slock); list_add_tail(&syscon->list, &syscon_list); - spin_unlock(&syscon_list_slock); return_ptr(syscon); @@ -169,7 +170,7 @@ static struct regmap *device_node_get_regmap(struct device_node *np, { struct syscon *entry, *syscon = NULL; - spin_lock(&syscon_list_slock); + mutex_lock(&syscon_list_lock); list_for_each_entry(entry, &syscon_list, list) if (entry->np == np) { @@ -177,11 +178,11 @@ static struct regmap *device_node_get_regmap(struct device_node *np, break; } - spin_unlock(&syscon_list_slock); - if (!syscon) syscon = of_syscon_register(np, check_res); + mutex_unlock(&syscon_list_lock); + if (IS_ERR(syscon)) return ERR_CAST(syscon); @@ -212,7 +213,7 @@ int of_syscon_register_regmap(struct device_node *np, struct regmap *regmap) return -ENOMEM; /* check if syscon entry already exists */ - spin_lock(&syscon_list_slock); + mutex_lock(&syscon_list_lock); list_for_each_entry(entry, &syscon_list, list) if (entry->np == np) { @@ -225,12 +226,12 @@ int of_syscon_register_regmap(struct device_node *np, struct regmap *regmap) /* register the regmap in syscon list */ list_add_tail(&syscon->list, &syscon_list); - spin_unlock(&syscon_list_slock); + mutex_unlock(&syscon_list_lock); return 0; err_unlock: - spin_unlock(&syscon_list_slock); + mutex_unlock(&syscon_list_lock); kfree(syscon); return ret; }
It is possible for multiple, simultaneous callers calling device_node_get_regmap() with the same node to fail to find an entry in the syscon_list. There is a period of time while the first caller is calling of_syscon_register() that subsequent callers also fail to find an entry in the syscon_list and then call of_syscon_register() a second time. Fix this by keeping the lock held until after of_syscon_register() completes and adds the node to syscon_list. Convert the spinlock to a mutex as many of the functions called in of_syscon_register() such as kzalloc() and of_clk_get() may sleep. Fixes: bdb0066df96e ("mfd: syscon: Decouple syscon interface from platform devices") Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Tested-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Signed-off-by: Rob Herring (Arm) <robh@kernel.org> --- drivers/mfd/syscon.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-)