From 4c13ac1cf0e40c1fea8993354e54822ef643425e Mon Sep 17 00:00:00 2001 From: Aaro Koskinen Date: Wed, 18 Nov 2015 21:59:01 +0200 Subject: hwrng: omap3-rom - convert timer to delayed work We cannot put the HW RNG to idle using a timer because we cannot disable clocks from atomic context. Use a delayed work instead. Fixes a warning with CONFIG_DEBUG_MUTEXES on Nokia N900 during boot. Reported-by: Sebastian Reichel Signed-off-by: Aaro Koskinen Signed-off-by: Herbert Xu --- drivers/char/hw_random/omap3-rom-rng.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'drivers/char') diff --git a/drivers/char/hw_random/omap3-rom-rng.c b/drivers/char/hw_random/omap3-rom-rng.c index a405cdcd8dd2..8da14f1a1f56 100644 --- a/drivers/char/hw_random/omap3-rom-rng.c +++ b/drivers/char/hw_random/omap3-rom-rng.c @@ -17,7 +17,7 @@ #include #include #include -#include +#include #include #include #include @@ -29,11 +29,11 @@ /* param1: ptr, param2: count, param3: flag */ static u32 (*omap3_rom_rng_call)(u32, u32, u32); -static struct timer_list idle_timer; +static struct delayed_work idle_work; static int rng_idle; static struct clk *rng_clk; -static void omap3_rom_rng_idle(unsigned long data) +static void omap3_rom_rng_idle(struct work_struct *work) { int r; @@ -51,7 +51,7 @@ static int omap3_rom_rng_get_random(void *buf, unsigned int count) u32 r; u32 ptr; - del_timer_sync(&idle_timer); + cancel_delayed_work_sync(&idle_work); if (rng_idle) { clk_prepare_enable(rng_clk); r = omap3_rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT); @@ -65,7 +65,7 @@ static int omap3_rom_rng_get_random(void *buf, unsigned int count) ptr = virt_to_phys(buf); r = omap3_rom_rng_call(ptr, count, RNG_GEN_HW); - mod_timer(&idle_timer, jiffies + msecs_to_jiffies(500)); + schedule_delayed_work(&idle_work, msecs_to_jiffies(500)); if (r != 0) return -EINVAL; return 0; @@ -102,7 +102,7 @@ static int omap3_rom_rng_probe(struct platform_device *pdev) return -EINVAL; } - setup_timer(&idle_timer, omap3_rom_rng_idle, 0); + INIT_DELAYED_WORK(&idle_work, omap3_rom_rng_idle); rng_clk = devm_clk_get(&pdev->dev, "ick"); if (IS_ERR(rng_clk)) { pr_err("unable to get RNG clock\n"); @@ -118,6 +118,7 @@ static int omap3_rom_rng_probe(struct platform_device *pdev) static int omap3_rom_rng_remove(struct platform_device *pdev) { + cancel_delayed_work_sync(&idle_work); hwrng_unregister(&omap3_rom_rng_ops); clk_disable_unprepare(rng_clk); return 0; -- cgit v1.2.3 From 1ab87298cb59b649d8d648d25dc15b36ab865f5a Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Fri, 27 Nov 2015 16:50:43 +0100 Subject: hwrng: core - sleep interruptible in read hwrng kthread can be waiting via hwrng_fillfn for some data from a rng like virtio-rng: hwrng D ffff880093e17798 0 382 2 0x00000000 ... Call Trace: [] wait_for_completion_killable+0x96/0x210 [] virtio_read+0x57/0xf0 [virtio_rng] [] hwrng_fillfn+0x75/0x130 [] kthread+0xf3/0x110 And when some user program tries to read the /dev node in this state, we get: rngd D ffff880093e17798 0 762 1 0x00000004 ... Call Trace: [] mutex_lock_nested+0x15c/0x3e0 [] rng_dev_read+0x6e/0x240 [] __vfs_read+0x28/0xe0 [] vfs_read+0x83/0x130 And this is indeed unkillable. So use mutex_lock_interruptible instead of mutex_lock in rng_dev_read and exit immediatelly when interrupted. And possibly return already read data, if any (as POSIX allows). v2: use ERESTARTSYS instead of EINTR Signed-off-by: Jiri Slaby Cc: Matt Mackall Cc: Herbert Xu Cc: Signed-off-by: Herbert Xu --- drivers/char/hw_random/core.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'drivers/char') diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index 6f497aa1b276..9203f2d130c0 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -238,7 +238,10 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf, goto out; } - mutex_lock(&reading_mutex); + if (mutex_lock_interruptible(&reading_mutex)) { + err = -ERESTARTSYS; + goto out_put; + } if (!data_avail) { bytes_read = rng_get_data(rng, rng_buffer, rng_buffer_size(), @@ -288,6 +291,7 @@ out: out_unlock_reading: mutex_unlock(&reading_mutex); +out_put: put_rng(rng); goto out; } -- cgit v1.2.3