Message-ID: <3jpwmb4zt7ykjclzcqmc6rkhmzl4vydefrece7eirnrltcryod@fcmmakzfzapf>
Date: Fri, 7 Feb 2025 17:36:12 +0100
From: Thierry Reding <thierry.reding@...il.com>
To: rusingh@...hat.com
Cc: airlied@...il.com, simona@...ll.ch, jonathanh@...dia.com, 
	mperttunen@...dia.com, linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpu: host1x: Fix a use of uninitialized mutex

On Thu, Feb 06, 2025 at 03:58:03PM +0000, rusingh@...hat.com wrote:
> From: Rupinderjit Singh <rusingh@...hat.com>
> 
> commit c8347f915e67 ("gpu: host1x: Fix boot regression for Tegra")
> caused a use of uninitialized mutex leading to below warning when
> CONFIG_DEBUG_MUTEXES and CONFIG_DEBUG_LOCK_ALLOC are enabled.
> 
> [   41.662843] ------------[ cut here ]------------
> [   41.663012] DEBUG_LOCKS_WARN_ON(lock->magic != lock)
> [   41.663035] WARNING: CPU: 4 PID: 794 at kernel/locking/mutex.c:587 __mutex_lock+0x670/0x878
> [   41.663458] Modules linked in: rtw88_8822c(+) bluetooth(+) rtw88_pci rtw88_core mac80211 aquantia libarc4 crc_itu_t cfg80211 tegra194_cpufreq dwmac_tegra(+) arm_dsu_pmu stmmac_platform stmmac pcs_xpcs rfkill at24 host1x(+) tegra_bpmp_thermal ramoops reed_solomon fuse loop nfnetlink xfs mmc_block rpmb_core ucsi_ccg ina3221 crct10dif_ce xhci_tegra ghash_ce lm90 sha2_ce sha256_arm64 sha1_ce sdhci_tegra pwm_fan sdhci_pltfm sdhci gpio_keys rtc_tegra cqhci mmc_core phy_tegra_xusb i2c_tegra tegra186_gpc_dma i2c_tegra_bpmp spi_tegra114 dm_mirror dm_region_hash dm_log dm_mod
> [   41.665078] CPU: 4 UID: 0 PID: 794 Comm: (udev-worker) Not tainted 6.11.0-29.31_1538613708.el10.aarch64+debug #1
> [   41.665838] Hardware name: NVIDIA NVIDIA Jetson AGX Orin Developer Kit/Jetson, BIOS 36.3.0-gcid-35594366 02/26/2024
> [   41.672555] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [   41.679636] pc : __mutex_lock+0x670/0x878
> [   41.683834] lr : __mutex_lock+0x670/0x878
> [   41.688035] sp : ffff800084b77090
> [   41.691446] x29: ffff800084b77160 x28: ffffdd4bebf7b000 x27: ffffdd4be96b1000
> [   41.698799] x26: 1fffe0002308361c x25: 1ffff0001096ee18 x24: 0000000000000000
> [   41.706149] x23: 0000000000000000 x22: 0000000000000002 x21: ffffdd4be6e3c7a0
> [   41.713500] x20: ffff800084b770f0 x19: ffff00011841b1e8 x18: 0000000000000000
> [   41.720675] x17: 0000000000000000 x16: 0000000000000000 x15: 0720072007200720
> [   41.728023] x14: 0000000000000000 x13: 0000000000000001 x12: ffff6001a96eaab3
> [   41.735375] x11: 1fffe001a96eaab2 x10: ffff6001a96eaab2 x9 : ffffdd4be4838bbc
> [   41.742723] x8 : 00009ffe5691554e x7 : ffff000d4b755593 x6 : 0000000000000001
> [   41.749985] x5 : ffff000d4b755590 x4 : 1fffe0001d88f001 x3 : dfff800000000000
> [   41.756988] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0000ec478000
> [   41.764251] Call trace:
> [   41.766695]  __mutex_lock+0x670/0x878
> [   41.770373]  mutex_lock_nested+0x2c/0x40
> [   41.774134]  host1x_intr_start+0x54/0xf8 [host1x]
> [   41.778863]  host1x_runtime_resume+0x150/0x228 [host1x]
> [   41.783935]  pm_generic_runtime_resume+0x84/0xc8
> [   41.788485]  __rpm_callback+0xa0/0x478
> [   41.792422]  rpm_callback+0x15c/0x1a8
> [   41.795922]  rpm_resume+0x698/0xc08
> [   41.799597]  __pm_runtime_resume+0xa8/0x140
> [   41.803621]  host1x_probe+0x810/0xbc0 [host1x]
> [   41.807909]  platform_probe+0xcc/0x1a8
> [   41.811845]  really_probe+0x188/0x800
> [   41.815347]  __driver_probe_device+0x164/0x360
> [   41.819810]  driver_probe_device+0x64/0x1a8
> [   41.823834]  __driver_attach+0x180/0x490
> [   41.827773]  bus_for_each_dev+0x104/0x1a0
> [   41.831797]  driver_attach+0x44/0x68
> [   41.835296]  bus_add_driver+0x23c/0x4e8
> [   41.839235]  driver_register+0x15c/0x3a8
> [   41.843170]  __platform_register_drivers+0xa4/0x208
> [   41.848159]  tegra_host1x_init+0x4c/0xff8 [host1x]
> [   41.853147]  do_one_initcall+0xd4/0x380
> [   41.856997]  do_init_module+0x1dc/0x698
> [   41.860758]  load_module+0xc70/0x1300
> [   41.864435]  __do_sys_init_module+0x1a8/0x1d0
> [   41.868721]  __arm64_sys_init_module+0x74/0xb0
> [   41.873183]  invoke_syscall.constprop.0+0xdc/0x1e8
> [   41.877997]  do_el0_svc+0x154/0x1d0
> [   41.881671]  el0_svc+0x54/0x140
> [   41.884820]  el0t_64_sync_handler+0x120/0x130
> [   41.889285]  el0t_64_sync+0x1a4/0x1a8
> [   41.892960] irq event stamp: 69737
> [   41.896370] hardirqs last  enabled at (69737): [<ffffdd4be6d7768c>] _raw_spin_unlock_irqrestore+0x44/0xe8
> [   41.905739] hardirqs last disabled at (69736): [<ffffdd4be59dcd40>] clk_enable_lock+0x98/0x198
> [   41.914314] softirqs last  enabled at (68082): [<ffffdd4be466b1d0>] handle_softirqs+0x4c8/0x890
> [   41.922977] softirqs last disabled at (67945): [<ffffdd4be44f02a4>] __do_softirq+0x1c/0x28
> [   41.931289] ---[ end trace 0000000000000000 ]---
> 
> Inside the probe function when pm_runtime_enable() is called,
> the PM core invokes a resume callback if the device Host1x is
> in a suspended state. As it can be seen in the logs above,
> this leads to host1x_intr_start() function call which is
> trying to acquire a mutex lock. But, the function
> host_intr_init() only gets called after the pm_runtime_enable()
> where mutex is initialised leading to the use of mutex
> prior to its initialisation.
> 
> Fix this by moving the mutex initialisation prior to the runtime
> PM enablement function pm_runtime_enable() in probe.
> 
> Fixes: c8347f915e67 ("gpu: host1x: Fix boot regression for Tegra")
> Signed-off-by: Rupinderjit Singh <rusingh@...hat.com>
> ---
>  drivers/gpu/host1x/dev.c  | 2 ++
>  drivers/gpu/host1x/intr.c | 2 --
>  2 files changed, 2 insertions(+), 2 deletions(-)

Applied to drm-misc-fixes, thanks.

Thierry

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