| Message ID | 20230822180208.95556-4-robdclark@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | drm/msm+PM+icc: Make job_run() reclaim-safe | expand |
On Tue, Aug 22, 2023 at 8:02 PM Rob Clark <robdclark@gmail.com> wrote: > > From: Rob Clark <robdclark@chromium.org> > > In the process of adding lockdep annotation for drm GPU scheduler's > job_run() to detect potential deadlock against shrinker/reclaim, I hit > this lockdep splat: > > ====================================================== > WARNING: possible circular locking dependency detected > 6.2.0-rc8-debug+ #558 Tainted: G W > ------------------------------------------------------ > ring0/125 is trying to acquire lock: > ffffffd6d6ce0f28 (dev_pm_qos_mtx){+.+.}-{3:3}, at: dev_pm_qos_update_request+0x38/0x68 > > but task is already holding lock: > ffffff8087239208 (&gpu->active_lock){+.+.}-{3:3}, at: msm_gpu_submit+0xec/0x178 > > which lock already depends on the new lock. > > the existing dependency chain (in reverse order) is: > > -> #4 (&gpu->active_lock){+.+.}-{3:3}: > __mutex_lock+0xcc/0x3c8 > mutex_lock_nested+0x30/0x44 > msm_gpu_submit+0xec/0x178 > msm_job_run+0x78/0x150 > drm_sched_main+0x290/0x370 > kthread+0xf0/0x100 > ret_from_fork+0x10/0x20 > > -> #3 (dma_fence_map){++++}-{0:0}: > __dma_fence_might_wait+0x74/0xc0 > dma_resv_lockdep+0x1f4/0x2f4 > do_one_initcall+0x104/0x2bc > kernel_init_freeable+0x344/0x34c > kernel_init+0x30/0x134 > ret_from_fork+0x10/0x20 > > -> #2 (mmu_notifier_invalidate_range_start){+.+.}-{0:0}: > fs_reclaim_acquire+0x80/0xa8 > slab_pre_alloc_hook.constprop.0+0x40/0x25c > __kmem_cache_alloc_node+0x60/0x1cc > __kmalloc+0xd8/0x100 > topology_parse_cpu_capacity+0x8c/0x178 > get_cpu_for_node+0x88/0xc4 > parse_cluster+0x1b0/0x28c > parse_cluster+0x8c/0x28c > init_cpu_topology+0x168/0x188 > smp_prepare_cpus+0x24/0xf8 > kernel_init_freeable+0x18c/0x34c > kernel_init+0x30/0x134 > ret_from_fork+0x10/0x20 > > -> #1 (fs_reclaim){+.+.}-{0:0}: > __fs_reclaim_acquire+0x3c/0x48 > fs_reclaim_acquire+0x54/0xa8 > slab_pre_alloc_hook.constprop.0+0x40/0x25c > __kmem_cache_alloc_node+0x60/0x1cc > kmalloc_trace+0x50/0xa8 > dev_pm_qos_constraints_allocate+0x38/0x100 > __dev_pm_qos_add_request+0xb0/0x1e8 > dev_pm_qos_add_request+0x58/0x80 > dev_pm_qos_expose_latency_limit+0x60/0x13c > register_cpu+0x12c/0x130 > topology_init+0xac/0xbc > do_one_initcall+0x104/0x2bc > kernel_init_freeable+0x344/0x34c > kernel_init+0x30/0x134 > ret_from_fork+0x10/0x20 > > -> #0 (dev_pm_qos_mtx){+.+.}-{3:3}: > __lock_acquire+0xe00/0x1060 > lock_acquire+0x1e0/0x2f8 > __mutex_lock+0xcc/0x3c8 > mutex_lock_nested+0x30/0x44 > dev_pm_qos_update_request+0x38/0x68 > msm_devfreq_boost+0x40/0x70 > msm_devfreq_active+0xc0/0xf0 > msm_gpu_submit+0x10c/0x178 > msm_job_run+0x78/0x150 > drm_sched_main+0x290/0x370 > kthread+0xf0/0x100 > ret_from_fork+0x10/0x20 > > other info that might help us debug this: > > Chain exists of: > dev_pm_qos_mtx --> dma_fence_map --> &gpu->active_lock > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(&gpu->active_lock); > lock(dma_fence_map); > lock(&gpu->active_lock); > lock(dev_pm_qos_mtx); > > *** DEADLOCK *** > > 3 locks held by ring0/123: > #0: ffffff8087251170 (&gpu->lock){+.+.}-{3:3}, at: msm_job_run+0x64/0x150 > #1: ffffffd00b0e57e8 (dma_fence_map){++++}-{0:0}, at: msm_job_run+0x68/0x150 > #2: ffffff8087251208 (&gpu->active_lock){+.+.}-{3:3}, at: msm_gpu_submit+0xec/0x178 > > stack backtrace: > CPU: 6 PID: 123 Comm: ring0 Not tainted 6.2.0-rc8-debug+ #559 > Hardware name: Google Lazor (rev1 - 2) with LTE (DT) > Call trace: > dump_backtrace.part.0+0xb4/0xf8 > show_stack+0x20/0x38 > dump_stack_lvl+0x9c/0xd0 > dump_stack+0x18/0x34 > print_circular_bug+0x1b4/0x1f0 > check_noncircular+0x78/0xac > __lock_acquire+0xe00/0x1060 > lock_acquire+0x1e0/0x2f8 > __mutex_lock+0xcc/0x3c8 > mutex_lock_nested+0x30/0x44 > dev_pm_qos_update_request+0x38/0x68 > msm_devfreq_boost+0x40/0x70 > msm_devfreq_active+0xc0/0xf0 > msm_gpu_submit+0x10c/0x178 > msm_job_run+0x78/0x150 > drm_sched_main+0x290/0x370 > kthread+0xf0/0x100 > ret_from_fork+0x10/0x20 > > The issue is that dev_pm_qos_mtx is held in the runpm suspend/resume (or > freq change) path, but it is also held across allocations that could > recurse into shrinker. > > Solve this by changing dev_pm_qos_constraints_allocate() into a function > that can be called unconditionally before the device qos object is > needed and before aquiring dev_pm_qos_mtx. This way the allocations can acquiring > be done without holding the mutex. In the case that we raced with > another thread to allocate the qos object, detect this *after* acquiring > the dev_pm_qos_mtx and simply free the redundant allocations. > > Suggested-by: Rafael J. Wysocki <rafael@kernel.org> > Signed-off-by: Rob Clark <robdclark@chromium.org> Please feel free to add Acked-by: Rafael J. Wysocki <rafael@kernel.org> to this patch and the next 2 PM QoS ones in this series. Thanks! > --- > drivers/base/power/qos.c | 76 +++++++++++++++++++++++++++++----------- > 1 file changed, 56 insertions(+), 20 deletions(-) > > diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c > index 8e93167f1783..7e95760d16dc 100644 > --- a/drivers/base/power/qos.c > +++ b/drivers/base/power/qos.c > @@ -185,27 +185,33 @@ static int apply_constraint(struct dev_pm_qos_request *req, > } > > /* > - * dev_pm_qos_constraints_allocate > + * dev_pm_qos_constraints_allocate: Allocate and initializes qos constraints > * @dev: device to allocate data for > * > - * Called at the first call to add_request, for constraint data allocation > - * Must be called with the dev_pm_qos_mtx mutex held > + * Called to allocate constraints before dev_pm_qos_mtx mutex is held. Should > + * be matched with a call to dev_pm_qos_constraints_set() once dev_pm_qos_mtx > + * is held. > */ > -static int dev_pm_qos_constraints_allocate(struct device *dev) > +static struct dev_pm_qos *dev_pm_qos_constraints_allocate(struct device *dev) > { > struct dev_pm_qos *qos; > struct pm_qos_constraints *c; > struct blocking_notifier_head *n; > > - qos = kzalloc(sizeof(*qos), GFP_KERNEL); > + /* > + * If constraints are already allocated, we can skip speculatively > + * allocating a new one, as we don't have to work about qos transitioning > + * from non-null to null. The constraints are only freed on device > + * removal. > + */ > + if (dev->power.qos) > + return NULL; > + > + qos = kzalloc(sizeof(*qos) + 3 * sizeof(*n), GFP_KERNEL); > if (!qos) > - return -ENOMEM; > + return NULL; > > - n = kzalloc(3 * sizeof(*n), GFP_KERNEL); > - if (!n) { > - kfree(qos); > - return -ENOMEM; > - } > + n = (struct blocking_notifier_head *)(qos + 1); > > c = &qos->resume_latency; > plist_head_init(&c->list); > @@ -227,11 +233,29 @@ static int dev_pm_qos_constraints_allocate(struct device *dev) > > INIT_LIST_HEAD(&qos->flags.list); > > + return qos; > +} > + > +/* > + * dev_pm_qos_constraints_set: Ensure dev->power.qos is set > + * > + * If dev->power.qos is already set, free the newly allocated qos constraints. > + * Otherwise set dev->power.qos. Must be called with dev_pm_qos_mtx held. > + * > + * This split unsynchronized allocation and synchronized set moves allocation > + * out from under dev_pm_qos_mtx, so that lockdep does does not get angry about > + * drivers which use dev_pm_qos in paths related to shrinker/reclaim. > + */ > +static void dev_pm_qos_constraints_set(struct device *dev, struct dev_pm_qos *qos) > +{ > + if (dev->power.qos) { > + kfree(qos); > + return; > + } > + > spin_lock_irq(&dev->power.lock); > dev->power.qos = qos; > spin_unlock_irq(&dev->power.lock); > - > - return 0; > } > > static void __dev_pm_qos_hide_latency_limit(struct device *dev); > @@ -309,7 +333,6 @@ void dev_pm_qos_constraints_destroy(struct device *dev) > dev->power.qos = ERR_PTR(-ENODEV); > spin_unlock_irq(&dev->power.lock); > > - kfree(qos->resume_latency.notifiers); > kfree(qos); > > out: > @@ -341,7 +364,7 @@ static int __dev_pm_qos_add_request(struct device *dev, > if (IS_ERR(dev->power.qos)) > ret = -ENODEV; > else if (!dev->power.qos) > - ret = dev_pm_qos_constraints_allocate(dev); > + ret = -ENOMEM; > > trace_dev_pm_qos_add_request(dev_name(dev), type, value); > if (ret) > @@ -388,9 +411,11 @@ static int __dev_pm_qos_add_request(struct device *dev, > int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req, > enum dev_pm_qos_req_type type, s32 value) > { > + struct dev_pm_qos *qos = dev_pm_qos_constraints_allocate(dev); > int ret; > > mutex_lock(&dev_pm_qos_mtx); > + dev_pm_qos_constraints_set(dev, qos); > ret = __dev_pm_qos_add_request(dev, req, type, value); > mutex_unlock(&dev_pm_qos_mtx); > return ret; > @@ -535,14 +560,15 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request); > int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier, > enum dev_pm_qos_req_type type) > { > + struct dev_pm_qos *qos = dev_pm_qos_constraints_allocate(dev); > int ret = 0; > > mutex_lock(&dev_pm_qos_mtx); > > + dev_pm_qos_constraints_set(dev, qos); > + > if (IS_ERR(dev->power.qos)) > ret = -ENODEV; > - else if (!dev->power.qos) > - ret = dev_pm_qos_constraints_allocate(dev); > > if (ret) > goto unlock; > @@ -903,12 +929,22 @@ s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev) > */ > int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val) > { > - int ret; > + struct dev_pm_qos *qos = dev_pm_qos_constraints_allocate(dev); > + int ret = 0; > > mutex_lock(&dev_pm_qos_mtx); > > - if (IS_ERR_OR_NULL(dev->power.qos) > - || !dev->power.qos->latency_tolerance_req) { > + dev_pm_qos_constraints_set(dev, qos); > + > + if (IS_ERR(dev->power.qos)) > + ret = -ENODEV; > + else if (!dev->power.qos) > + ret = -ENOMEM; > + > + if (ret) > + goto out; > + > + if (!dev->power.qos->latency_tolerance_req) { > struct dev_pm_qos_request *req; > > if (val < 0) { > -- > 2.41.0 >
On Tue, Aug 22, 2023 at 11:48 AM Rafael J. Wysocki <rafael@kernel.org> wrote: > > On Tue, Aug 22, 2023 at 8:02 PM Rob Clark <robdclark@gmail.com> wrote: > > > > From: Rob Clark <robdclark@chromium.org> > > > > In the process of adding lockdep annotation for drm GPU scheduler's > > job_run() to detect potential deadlock against shrinker/reclaim, I hit > > this lockdep splat: > > > > ====================================================== > > WARNING: possible circular locking dependency detected > > 6.2.0-rc8-debug+ #558 Tainted: G W > > ------------------------------------------------------ > > ring0/125 is trying to acquire lock: > > ffffffd6d6ce0f28 (dev_pm_qos_mtx){+.+.}-{3:3}, at: dev_pm_qos_update_request+0x38/0x68 > > > > but task is already holding lock: > > ffffff8087239208 (&gpu->active_lock){+.+.}-{3:3}, at: msm_gpu_submit+0xec/0x178 > > > > which lock already depends on the new lock. > > > > the existing dependency chain (in reverse order) is: > > > > -> #4 (&gpu->active_lock){+.+.}-{3:3}: > > __mutex_lock+0xcc/0x3c8 > > mutex_lock_nested+0x30/0x44 > > msm_gpu_submit+0xec/0x178 > > msm_job_run+0x78/0x150 > > drm_sched_main+0x290/0x370 > > kthread+0xf0/0x100 > > ret_from_fork+0x10/0x20 > > > > -> #3 (dma_fence_map){++++}-{0:0}: > > __dma_fence_might_wait+0x74/0xc0 > > dma_resv_lockdep+0x1f4/0x2f4 > > do_one_initcall+0x104/0x2bc > > kernel_init_freeable+0x344/0x34c > > kernel_init+0x30/0x134 > > ret_from_fork+0x10/0x20 > > > > -> #2 (mmu_notifier_invalidate_range_start){+.+.}-{0:0}: > > fs_reclaim_acquire+0x80/0xa8 > > slab_pre_alloc_hook.constprop.0+0x40/0x25c > > __kmem_cache_alloc_node+0x60/0x1cc > > __kmalloc+0xd8/0x100 > > topology_parse_cpu_capacity+0x8c/0x178 > > get_cpu_for_node+0x88/0xc4 > > parse_cluster+0x1b0/0x28c > > parse_cluster+0x8c/0x28c > > init_cpu_topology+0x168/0x188 > > smp_prepare_cpus+0x24/0xf8 > > kernel_init_freeable+0x18c/0x34c > > kernel_init+0x30/0x134 > > ret_from_fork+0x10/0x20 > > > > -> #1 (fs_reclaim){+.+.}-{0:0}: > > __fs_reclaim_acquire+0x3c/0x48 > > fs_reclaim_acquire+0x54/0xa8 > > slab_pre_alloc_hook.constprop.0+0x40/0x25c > > __kmem_cache_alloc_node+0x60/0x1cc > > kmalloc_trace+0x50/0xa8 > > dev_pm_qos_constraints_allocate+0x38/0x100 > > __dev_pm_qos_add_request+0xb0/0x1e8 > > dev_pm_qos_add_request+0x58/0x80 > > dev_pm_qos_expose_latency_limit+0x60/0x13c > > register_cpu+0x12c/0x130 > > topology_init+0xac/0xbc > > do_one_initcall+0x104/0x2bc > > kernel_init_freeable+0x344/0x34c > > kernel_init+0x30/0x134 > > ret_from_fork+0x10/0x20 > > > > -> #0 (dev_pm_qos_mtx){+.+.}-{3:3}: > > __lock_acquire+0xe00/0x1060 > > lock_acquire+0x1e0/0x2f8 > > __mutex_lock+0xcc/0x3c8 > > mutex_lock_nested+0x30/0x44 > > dev_pm_qos_update_request+0x38/0x68 > > msm_devfreq_boost+0x40/0x70 > > msm_devfreq_active+0xc0/0xf0 > > msm_gpu_submit+0x10c/0x178 > > msm_job_run+0x78/0x150 > > drm_sched_main+0x290/0x370 > > kthread+0xf0/0x100 > > ret_from_fork+0x10/0x20 > > > > other info that might help us debug this: > > > > Chain exists of: > > dev_pm_qos_mtx --> dma_fence_map --> &gpu->active_lock > > > > Possible unsafe locking scenario: > > > > CPU0 CPU1 > > ---- ---- > > lock(&gpu->active_lock); > > lock(dma_fence_map); > > lock(&gpu->active_lock); > > lock(dev_pm_qos_mtx); > > > > *** DEADLOCK *** > > > > 3 locks held by ring0/123: > > #0: ffffff8087251170 (&gpu->lock){+.+.}-{3:3}, at: msm_job_run+0x64/0x150 > > #1: ffffffd00b0e57e8 (dma_fence_map){++++}-{0:0}, at: msm_job_run+0x68/0x150 > > #2: ffffff8087251208 (&gpu->active_lock){+.+.}-{3:3}, at: msm_gpu_submit+0xec/0x178 > > > > stack backtrace: > > CPU: 6 PID: 123 Comm: ring0 Not tainted 6.2.0-rc8-debug+ #559 > > Hardware name: Google Lazor (rev1 - 2) with LTE (DT) > > Call trace: > > dump_backtrace.part.0+0xb4/0xf8 > > show_stack+0x20/0x38 > > dump_stack_lvl+0x9c/0xd0 > > dump_stack+0x18/0x34 > > print_circular_bug+0x1b4/0x1f0 > > check_noncircular+0x78/0xac > > __lock_acquire+0xe00/0x1060 > > lock_acquire+0x1e0/0x2f8 > > __mutex_lock+0xcc/0x3c8 > > mutex_lock_nested+0x30/0x44 > > dev_pm_qos_update_request+0x38/0x68 > > msm_devfreq_boost+0x40/0x70 > > msm_devfreq_active+0xc0/0xf0 > > msm_gpu_submit+0x10c/0x178 > > msm_job_run+0x78/0x150 > > drm_sched_main+0x290/0x370 > > kthread+0xf0/0x100 > > ret_from_fork+0x10/0x20 > > > > The issue is that dev_pm_qos_mtx is held in the runpm suspend/resume (or > > freq change) path, but it is also held across allocations that could > > recurse into shrinker. > > > > Solve this by changing dev_pm_qos_constraints_allocate() into a function > > that can be called unconditionally before the device qos object is > > needed and before aquiring dev_pm_qos_mtx. This way the allocations can > > acquiring > > > be done without holding the mutex. In the case that we raced with > > another thread to allocate the qos object, detect this *after* acquiring > > the dev_pm_qos_mtx and simply free the redundant allocations. > > > > Suggested-by: Rafael J. Wysocki <rafael@kernel.org> > > Signed-off-by: Rob Clark <robdclark@chromium.org> > > Please feel free to add > > Acked-by: Rafael J. Wysocki <rafael@kernel.org> > > to this patch and the next 2 PM QoS ones in this series. > thanks > Thanks! > > > --- > > drivers/base/power/qos.c | 76 +++++++++++++++++++++++++++++----------- > > 1 file changed, 56 insertions(+), 20 deletions(-) > > > > diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c > > index 8e93167f1783..7e95760d16dc 100644 > > --- a/drivers/base/power/qos.c > > +++ b/drivers/base/power/qos.c > > @@ -185,27 +185,33 @@ static int apply_constraint(struct dev_pm_qos_request *req, > > } > > > > /* > > - * dev_pm_qos_constraints_allocate > > + * dev_pm_qos_constraints_allocate: Allocate and initializes qos constraints > > * @dev: device to allocate data for > > * > > - * Called at the first call to add_request, for constraint data allocation > > - * Must be called with the dev_pm_qos_mtx mutex held > > + * Called to allocate constraints before dev_pm_qos_mtx mutex is held. Should > > + * be matched with a call to dev_pm_qos_constraints_set() once dev_pm_qos_mtx > > + * is held. > > */ > > -static int dev_pm_qos_constraints_allocate(struct device *dev) > > +static struct dev_pm_qos *dev_pm_qos_constraints_allocate(struct device *dev) > > { > > struct dev_pm_qos *qos; > > struct pm_qos_constraints *c; > > struct blocking_notifier_head *n; > > > > - qos = kzalloc(sizeof(*qos), GFP_KERNEL); > > + /* > > + * If constraints are already allocated, we can skip speculatively > > + * allocating a new one, as we don't have to work about qos transitioning > > + * from non-null to null. The constraints are only freed on device > > + * removal. > > + */ > > + if (dev->power.qos) > > + return NULL; > > + > > + qos = kzalloc(sizeof(*qos) + 3 * sizeof(*n), GFP_KERNEL); > > if (!qos) > > - return -ENOMEM; > > + return NULL; > > > > - n = kzalloc(3 * sizeof(*n), GFP_KERNEL); > > - if (!n) { > > - kfree(qos); > > - return -ENOMEM; > > - } > > + n = (struct blocking_notifier_head *)(qos + 1); > > > > c = &qos->resume_latency; > > plist_head_init(&c->list); > > @@ -227,11 +233,29 @@ static int dev_pm_qos_constraints_allocate(struct device *dev) > > > > INIT_LIST_HEAD(&qos->flags.list); > > > > + return qos; > > +} > > + > > +/* > > + * dev_pm_qos_constraints_set: Ensure dev->power.qos is set > > + * > > + * If dev->power.qos is already set, free the newly allocated qos constraints. > > + * Otherwise set dev->power.qos. Must be called with dev_pm_qos_mtx held. > > + * > > + * This split unsynchronized allocation and synchronized set moves allocation > > + * out from under dev_pm_qos_mtx, so that lockdep does does not get angry about > > + * drivers which use dev_pm_qos in paths related to shrinker/reclaim. > > + */ > > +static void dev_pm_qos_constraints_set(struct device *dev, struct dev_pm_qos *qos) > > +{ > > + if (dev->power.qos) { > > + kfree(qos); > > + return; > > + } > > + > > spin_lock_irq(&dev->power.lock); > > dev->power.qos = qos; > > spin_unlock_irq(&dev->power.lock); > > - > > - return 0; > > } > > > > static void __dev_pm_qos_hide_latency_limit(struct device *dev); > > @@ -309,7 +333,6 @@ void dev_pm_qos_constraints_destroy(struct device *dev) > > dev->power.qos = ERR_PTR(-ENODEV); > > spin_unlock_irq(&dev->power.lock); > > > > - kfree(qos->resume_latency.notifiers); > > kfree(qos); > > > > out: > > @@ -341,7 +364,7 @@ static int __dev_pm_qos_add_request(struct device *dev, > > if (IS_ERR(dev->power.qos)) > > ret = -ENODEV; > > else if (!dev->power.qos) > > - ret = dev_pm_qos_constraints_allocate(dev); > > + ret = -ENOMEM; > > > > trace_dev_pm_qos_add_request(dev_name(dev), type, value); > > if (ret) > > @@ -388,9 +411,11 @@ static int __dev_pm_qos_add_request(struct device *dev, > > int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req, > > enum dev_pm_qos_req_type type, s32 value) > > { > > + struct dev_pm_qos *qos = dev_pm_qos_constraints_allocate(dev); > > int ret; > > > > mutex_lock(&dev_pm_qos_mtx); > > + dev_pm_qos_constraints_set(dev, qos); > > ret = __dev_pm_qos_add_request(dev, req, type, value); > > mutex_unlock(&dev_pm_qos_mtx); > > return ret; > > @@ -535,14 +560,15 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request); > > int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier, > > enum dev_pm_qos_req_type type) > > { > > + struct dev_pm_qos *qos = dev_pm_qos_constraints_allocate(dev); > > int ret = 0; > > > > mutex_lock(&dev_pm_qos_mtx); > > > > + dev_pm_qos_constraints_set(dev, qos); > > + > > if (IS_ERR(dev->power.qos)) > > ret = -ENODEV; > > - else if (!dev->power.qos) > > - ret = dev_pm_qos_constraints_allocate(dev); > > > > if (ret) > > goto unlock; > > @@ -903,12 +929,22 @@ s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev) > > */ > > int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val) > > { > > - int ret; > > + struct dev_pm_qos *qos = dev_pm_qos_constraints_allocate(dev); > > + int ret = 0; > > > > mutex_lock(&dev_pm_qos_mtx); > > > > - if (IS_ERR_OR_NULL(dev->power.qos) > > - || !dev->power.qos->latency_tolerance_req) { > > + dev_pm_qos_constraints_set(dev, qos); > > + > > + if (IS_ERR(dev->power.qos)) > > + ret = -ENODEV; > > + else if (!dev->power.qos) > > + ret = -ENOMEM; > > + > > + if (ret) > > + goto out; > > + > > + if (!dev->power.qos->latency_tolerance_req) { > > struct dev_pm_qos_request *req; > > > > if (val < 0) { > > -- > > 2.41.0 > >
diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c index 8e93167f1783..7e95760d16dc 100644 --- a/drivers/base/power/qos.c +++ b/drivers/base/power/qos.c @@ -185,27 +185,33 @@ static int apply_constraint(struct dev_pm_qos_request *req, } /* - * dev_pm_qos_constraints_allocate + * dev_pm_qos_constraints_allocate: Allocate and initializes qos constraints * @dev: device to allocate data for * - * Called at the first call to add_request, for constraint data allocation - * Must be called with the dev_pm_qos_mtx mutex held + * Called to allocate constraints before dev_pm_qos_mtx mutex is held. Should + * be matched with a call to dev_pm_qos_constraints_set() once dev_pm_qos_mtx + * is held. */ -static int dev_pm_qos_constraints_allocate(struct device *dev) +static struct dev_pm_qos *dev_pm_qos_constraints_allocate(struct device *dev) { struct dev_pm_qos *qos; struct pm_qos_constraints *c; struct blocking_notifier_head *n; - qos = kzalloc(sizeof(*qos), GFP_KERNEL); + /* + * If constraints are already allocated, we can skip speculatively + * allocating a new one, as we don't have to work about qos transitioning + * from non-null to null. The constraints are only freed on device + * removal. + */ + if (dev->power.qos) + return NULL; + + qos = kzalloc(sizeof(*qos) + 3 * sizeof(*n), GFP_KERNEL); if (!qos) - return -ENOMEM; + return NULL; - n = kzalloc(3 * sizeof(*n), GFP_KERNEL); - if (!n) { - kfree(qos); - return -ENOMEM; - } + n = (struct blocking_notifier_head *)(qos + 1); c = &qos->resume_latency; plist_head_init(&c->list); @@ -227,11 +233,29 @@ static int dev_pm_qos_constraints_allocate(struct device *dev) INIT_LIST_HEAD(&qos->flags.list); + return qos; +} + +/* + * dev_pm_qos_constraints_set: Ensure dev->power.qos is set + * + * If dev->power.qos is already set, free the newly allocated qos constraints. + * Otherwise set dev->power.qos. Must be called with dev_pm_qos_mtx held. + * + * This split unsynchronized allocation and synchronized set moves allocation + * out from under dev_pm_qos_mtx, so that lockdep does does not get angry about + * drivers which use dev_pm_qos in paths related to shrinker/reclaim. + */ +static void dev_pm_qos_constraints_set(struct device *dev, struct dev_pm_qos *qos) +{ + if (dev->power.qos) { + kfree(qos); + return; + } + spin_lock_irq(&dev->power.lock); dev->power.qos = qos; spin_unlock_irq(&dev->power.lock); - - return 0; } static void __dev_pm_qos_hide_latency_limit(struct device *dev); @@ -309,7 +333,6 @@ void dev_pm_qos_constraints_destroy(struct device *dev) dev->power.qos = ERR_PTR(-ENODEV); spin_unlock_irq(&dev->power.lock); - kfree(qos->resume_latency.notifiers); kfree(qos); out: @@ -341,7 +364,7 @@ static int __dev_pm_qos_add_request(struct device *dev, if (IS_ERR(dev->power.qos)) ret = -ENODEV; else if (!dev->power.qos) - ret = dev_pm_qos_constraints_allocate(dev); + ret = -ENOMEM; trace_dev_pm_qos_add_request(dev_name(dev), type, value); if (ret) @@ -388,9 +411,11 @@ static int __dev_pm_qos_add_request(struct device *dev, int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req, enum dev_pm_qos_req_type type, s32 value) { + struct dev_pm_qos *qos = dev_pm_qos_constraints_allocate(dev); int ret; mutex_lock(&dev_pm_qos_mtx); + dev_pm_qos_constraints_set(dev, qos); ret = __dev_pm_qos_add_request(dev, req, type, value); mutex_unlock(&dev_pm_qos_mtx); return ret; @@ -535,14 +560,15 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request); int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier, enum dev_pm_qos_req_type type) { + struct dev_pm_qos *qos = dev_pm_qos_constraints_allocate(dev); int ret = 0; mutex_lock(&dev_pm_qos_mtx); + dev_pm_qos_constraints_set(dev, qos); + if (IS_ERR(dev->power.qos)) ret = -ENODEV; - else if (!dev->power.qos) - ret = dev_pm_qos_constraints_allocate(dev); if (ret) goto unlock; @@ -903,12 +929,22 @@ s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev) */ int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val) { - int ret; + struct dev_pm_qos *qos = dev_pm_qos_constraints_allocate(dev); + int ret = 0; mutex_lock(&dev_pm_qos_mtx); - if (IS_ERR_OR_NULL(dev->power.qos) - || !dev->power.qos->latency_tolerance_req) { + dev_pm_qos_constraints_set(dev, qos); + + if (IS_ERR(dev->power.qos)) + ret = -ENODEV; + else if (!dev->power.qos) + ret = -ENOMEM; + + if (ret) + goto out; + + if (!dev->power.qos->latency_tolerance_req) { struct dev_pm_qos_request *req; if (val < 0) {