updated version of SPI driver that now runs with real time priority and ... #147
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…nd makes use of the onemessage interface
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Just for reference, this pull request is based on this topic discussion, right? http://raspberrypi.org/phpBB3/viewtopic.php?f=44&t=19489 Really looking forward to see this integrated! |
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yes - correctly. BTW: Do you have an idea how we could export THE VideoCore Bus addresses in a sane manner to drivers like this? |
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Unfortunately I can not help here, I've been tracking the initial discussion and found this to be pretty interesting to a project that I want to test in near future, for a microcontroller fast data acquisition module that would also take advantage from the direct DMA access to userspace. I just wanted to make a reference to the original discussion so that others could track all of your previous work and see how important this may be! BTW, thank you for all your hard work! |
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No Problem - I was actually asking the Foundation if they could not also get the documentation for the Camera interface open as well - it is essentially a differential SPI interface with 2 Data lanes, so we could actually use the interface as well for SPI stuff - and actually read 2 datastreams (for ADCs) in parallel. This would be nice for my long-term-sonar imaging project where i would need to read out multiple ADCs syncronously at high frequencies... |
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What about pulling that patch in? BTW: as to DMA (from userspace), it seems as if the dmaer (DMAHelper) could get used to make direct DMA to/from userspace a possibility. Again this is a possibility for some sampling needs. With the 512MB RPIs this might be more of interrest, as more pages can get locked in memory... |
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This looks like great work! I'll be pulling this into my kernel right now and it should help performance for some work I'm doing on getting a radio kernel module up and running. I was worried about the SPI latencies you demonstrated on the RPi forums. I'll report back when I've had some time to test everything. Thanks for the good work! |
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I am closing this for now - a newer DMA version based on the upstream spi-BCM2835.c will appear at some point... |
popcornmix
pushed a commit
that referenced
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Oct 22, 2016
commit 8571410 upstream. When dma_common_free_remap, the input parameter 'size' may not be page aligned. And, met kernel warning when doing iommu dma for usb on i.MX8 platform: " WARNING: CPU: 0 PID: 869 at mm/vmalloc.c:70 vunmap_page_range+0x1cc/0x1d0() Modules linked in: CPU: 0 PID: 869 Comm: kworker/u8:2 Not tainted 4.1.12-00444-gc5f9d1d-dirty #147 Hardware name: Freescale i.MX8DV Sabreauto (DT) Workqueue: ci_otg ci_otg_work Call trace: [<ffffffc000089920>] dump_backtrace+0x0/0x124 [<ffffffc000089a54>] show_stack+0x10/0x1c [<ffffffc0006d1e6c>] dump_stack+0x84/0xc8 [<ffffffc0000b4568>] warn_slowpath_common+0x98/0xd0 [<ffffffc0000b4664>] warn_slowpath_null+0x14/0x20 [<ffffffc000170348>] vunmap_page_range+0x1c8/0x1d0 [<ffffffc000170388>] unmap_kernel_range+0x20/0x88 [<ffffffc000460ad0>] dma_common_free_remap+0x74/0x84 [<ffffffc0000940d8>] __iommu_free_attrs+0x9c/0x178 [<ffffffc0005032bc>] ehci_mem_cleanup+0x140/0x194 [<ffffffc000503548>] ehci_stop+0x8c/0xdc [<ffffffc0004e8258>] usb_remove_hcd+0xf0/0x1cc [<ffffffc000516bc0>] host_stop+0x1c/0x58 [<ffffffc000514240>] ci_otg_work+0xdc/0x120 [<ffffffc0000c9c34>] process_one_work+0x134/0x33c [<ffffffc0000c9f78>] worker_thread+0x13c/0x47c [<ffffffc0000cf43c>] kthread+0xd8/0xf0 " For dma_common_pages_remap: dma_common_pages_remap |->get_vm_area_caller |->__get_vm_area_node |->size = PAGE_ALIGN(size); Round up to page aligned So, in dma_common_free_remap, we also need a page aligned size, pass 'PAGE_ALIGN(size)' to unmap_kernel_range. Signed-off-by: Peng Fan <van.freenix@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
popcornmix
pushed a commit
that referenced
this pull request
Oct 22, 2016
commit 8571410 upstream. When dma_common_free_remap, the input parameter 'size' may not be page aligned. And, met kernel warning when doing iommu dma for usb on i.MX8 platform: " WARNING: CPU: 0 PID: 869 at mm/vmalloc.c:70 vunmap_page_range+0x1cc/0x1d0() Modules linked in: CPU: 0 PID: 869 Comm: kworker/u8:2 Not tainted 4.1.12-00444-gc5f9d1d-dirty #147 Hardware name: Freescale i.MX8DV Sabreauto (DT) Workqueue: ci_otg ci_otg_work Call trace: [<ffffffc000089920>] dump_backtrace+0x0/0x124 [<ffffffc000089a54>] show_stack+0x10/0x1c [<ffffffc0006d1e6c>] dump_stack+0x84/0xc8 [<ffffffc0000b4568>] warn_slowpath_common+0x98/0xd0 [<ffffffc0000b4664>] warn_slowpath_null+0x14/0x20 [<ffffffc000170348>] vunmap_page_range+0x1c8/0x1d0 [<ffffffc000170388>] unmap_kernel_range+0x20/0x88 [<ffffffc000460ad0>] dma_common_free_remap+0x74/0x84 [<ffffffc0000940d8>] __iommu_free_attrs+0x9c/0x178 [<ffffffc0005032bc>] ehci_mem_cleanup+0x140/0x194 [<ffffffc000503548>] ehci_stop+0x8c/0xdc [<ffffffc0004e8258>] usb_remove_hcd+0xf0/0x1cc [<ffffffc000516bc0>] host_stop+0x1c/0x58 [<ffffffc000514240>] ci_otg_work+0xdc/0x120 [<ffffffc0000c9c34>] process_one_work+0x134/0x33c [<ffffffc0000c9f78>] worker_thread+0x13c/0x47c [<ffffffc0000cf43c>] kthread+0xd8/0xf0 " For dma_common_pages_remap: dma_common_pages_remap |->get_vm_area_caller |->__get_vm_area_node |->size = PAGE_ALIGN(size); Round up to page aligned So, in dma_common_free_remap, we also need a page aligned size, pass 'PAGE_ALIGN(size)' to unmap_kernel_range. Signed-off-by: Peng Fan <van.freenix@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
popcornmix
pushed a commit
that referenced
this pull request
Oct 22, 2016
commit 8571410 upstream. When dma_common_free_remap, the input parameter 'size' may not be page aligned. And, met kernel warning when doing iommu dma for usb on i.MX8 platform: " WARNING: CPU: 0 PID: 869 at mm/vmalloc.c:70 vunmap_page_range+0x1cc/0x1d0() Modules linked in: CPU: 0 PID: 869 Comm: kworker/u8:2 Not tainted 4.1.12-00444-gc5f9d1d-dirty #147 Hardware name: Freescale i.MX8DV Sabreauto (DT) Workqueue: ci_otg ci_otg_work Call trace: [<ffffffc000089920>] dump_backtrace+0x0/0x124 [<ffffffc000089a54>] show_stack+0x10/0x1c [<ffffffc0006d1e6c>] dump_stack+0x84/0xc8 [<ffffffc0000b4568>] warn_slowpath_common+0x98/0xd0 [<ffffffc0000b4664>] warn_slowpath_null+0x14/0x20 [<ffffffc000170348>] vunmap_page_range+0x1c8/0x1d0 [<ffffffc000170388>] unmap_kernel_range+0x20/0x88 [<ffffffc000460ad0>] dma_common_free_remap+0x74/0x84 [<ffffffc0000940d8>] __iommu_free_attrs+0x9c/0x178 [<ffffffc0005032bc>] ehci_mem_cleanup+0x140/0x194 [<ffffffc000503548>] ehci_stop+0x8c/0xdc [<ffffffc0004e8258>] usb_remove_hcd+0xf0/0x1cc [<ffffffc000516bc0>] host_stop+0x1c/0x58 [<ffffffc000514240>] ci_otg_work+0xdc/0x120 [<ffffffc0000c9c34>] process_one_work+0x134/0x33c [<ffffffc0000c9f78>] worker_thread+0x13c/0x47c [<ffffffc0000cf43c>] kthread+0xd8/0xf0 " For dma_common_pages_remap: dma_common_pages_remap |->get_vm_area_caller |->__get_vm_area_node |->size = PAGE_ALIGN(size); Round up to page aligned So, in dma_common_free_remap, we also need a page aligned size, pass 'PAGE_ALIGN(size)' to unmap_kernel_range. Signed-off-by: Peng Fan <van.freenix@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
0lxb
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to 0lxb/rpi_linux
that referenced
this pull request
Jan 30, 2024
…find_and_get_node_by_id()
The BPF helper bpf_cgroup_from_id() calls kernfs_find_and_get_node_by_id()
which acquires kernfs_idr_lock, which is an non-raw non-IRQ-safe lock. This
can lead to deadlocks as bpf_cgroup_from_id() can be called from any BPF
programs including e.g. the ones that attach to functions which are holding
the scheduler rq lock.
Consider the following BPF program:
SEC("fentry/__set_cpus_allowed_ptr_locked")
int BPF_PROG(__set_cpus_allowed_ptr_locked, struct task_struct *p,
struct affinity_context *affn_ctx, struct rq *rq, struct rq_flags *rf)
{
struct cgroup *cgrp = bpf_cgroup_from_id(p->cgroups->dfl_cgrp->kn->id);
if (cgrp) {
bpf_printk("%d[%s] in %s", p->pid, p->comm, cgrp->kn->name);
bpf_cgroup_release(cgrp);
}
return 0;
}
__set_cpus_allowed_ptr_locked() is called with rq lock held and the above
BPF program calls bpf_cgroup_from_id() within leading to the following
lockdep warning:
=====================================================
WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
6.7.0-rc3-work-00053-g07124366a1d7-dirty raspberrypi#147 Not tainted
-----------------------------------------------------
repro/1620 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
ffffffff833b3688 (kernfs_idr_lock){+.+.}-{2:2}, at: kernfs_find_and_get_node_by_id+0x1e/0x70
and this task is already holding:
ffff888237ced698 (&rq->__lock){-.-.}-{2:2}, at: task_rq_lock+0x4e/0xf0
which would create a new lock dependency:
(&rq->__lock){-.-.}-{2:2} -> (kernfs_idr_lock){+.+.}-{2:2}
...
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(kernfs_idr_lock);
local_irq_disable();
lock(&rq->__lock);
lock(kernfs_idr_lock);
<Interrupt>
lock(&rq->__lock);
*** DEADLOCK ***
...
Call Trace:
dump_stack_lvl+0x55/0x70
dump_stack+0x10/0x20
__lock_acquire+0x781/0x2a40
lock_acquire+0xbf/0x1f0
_raw_spin_lock+0x2f/0x40
kernfs_find_and_get_node_by_id+0x1e/0x70
cgroup_get_from_id+0x21/0x240
bpf_cgroup_from_id+0xe/0x20
bpf_prog_98652316e9337a5a___set_cpus_allowed_ptr_locked+0x96/0x11a
bpf_trampoline_6442545632+0x4f/0x1000
__set_cpus_allowed_ptr_locked+0x5/0x5a0
sched_setaffinity+0x1b3/0x290
__x64_sys_sched_setaffinity+0x4f/0x60
do_syscall_64+0x40/0xe0
entry_SYSCALL_64_after_hwframe+0x46/0x4e
Let's fix it by protecting kernfs_node and kernfs_root with RCU and making
kernfs_find_and_get_node_by_id() acquire rcu_read_lock() instead of
kernfs_idr_lock.
This adds an rcu_head to kernfs_node making it larger by 16 bytes on 64bit.
Combined with the preceding rearrange patch, the net increase is 8 bytes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrea Righi <andrea.righi@canonical.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
popcornmix
pushed a commit
that referenced
this pull request
Apr 16, 2024
…find_and_get_node_by_id() [ Upstream commit 4207b55 ] The BPF helper bpf_cgroup_from_id() calls kernfs_find_and_get_node_by_id() which acquires kernfs_idr_lock, which is an non-raw non-IRQ-safe lock. This can lead to deadlocks as bpf_cgroup_from_id() can be called from any BPF programs including e.g. the ones that attach to functions which are holding the scheduler rq lock. Consider the following BPF program: SEC("fentry/__set_cpus_allowed_ptr_locked") int BPF_PROG(__set_cpus_allowed_ptr_locked, struct task_struct *p, struct affinity_context *affn_ctx, struct rq *rq, struct rq_flags *rf) { struct cgroup *cgrp = bpf_cgroup_from_id(p->cgroups->dfl_cgrp->kn->id); if (cgrp) { bpf_printk("%d[%s] in %s", p->pid, p->comm, cgrp->kn->name); bpf_cgroup_release(cgrp); } return 0; } __set_cpus_allowed_ptr_locked() is called with rq lock held and the above BPF program calls bpf_cgroup_from_id() within leading to the following lockdep warning: ===================================================== WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected 6.7.0-rc3-work-00053-g07124366a1d7-dirty #147 Not tainted ----------------------------------------------------- repro/1620 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: ffffffff833b3688 (kernfs_idr_lock){+.+.}-{2:2}, at: kernfs_find_and_get_node_by_id+0x1e/0x70 and this task is already holding: ffff888237ced698 (&rq->__lock){-.-.}-{2:2}, at: task_rq_lock+0x4e/0xf0 which would create a new lock dependency: (&rq->__lock){-.-.}-{2:2} -> (kernfs_idr_lock){+.+.}-{2:2} ... Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(kernfs_idr_lock); local_irq_disable(); lock(&rq->__lock); lock(kernfs_idr_lock); <Interrupt> lock(&rq->__lock); *** DEADLOCK *** ... Call Trace: dump_stack_lvl+0x55/0x70 dump_stack+0x10/0x20 __lock_acquire+0x781/0x2a40 lock_acquire+0xbf/0x1f0 _raw_spin_lock+0x2f/0x40 kernfs_find_and_get_node_by_id+0x1e/0x70 cgroup_get_from_id+0x21/0x240 bpf_cgroup_from_id+0xe/0x20 bpf_prog_98652316e9337a5a___set_cpus_allowed_ptr_locked+0x96/0x11a bpf_trampoline_6442545632+0x4f/0x1000 __set_cpus_allowed_ptr_locked+0x5/0x5a0 sched_setaffinity+0x1b3/0x290 __x64_sys_sched_setaffinity+0x4f/0x60 do_syscall_64+0x40/0xe0 entry_SYSCALL_64_after_hwframe+0x46/0x4e Let's fix it by protecting kernfs_node and kernfs_root with RCU and making kernfs_find_and_get_node_by_id() acquire rcu_read_lock() instead of kernfs_idr_lock. This adds an rcu_head to kernfs_node making it larger by 16 bytes on 64bit. Combined with the preceding rearrange patch, the net increase is 8 bytes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrea Righi <andrea.righi@canonical.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Link: https://lore.kernel.org/r/20240109214828.252092-4-tj@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
popcornmix
pushed a commit
that referenced
this pull request
Apr 18, 2024
…find_and_get_node_by_id() [ Upstream commit 4207b55 ] The BPF helper bpf_cgroup_from_id() calls kernfs_find_and_get_node_by_id() which acquires kernfs_idr_lock, which is an non-raw non-IRQ-safe lock. This can lead to deadlocks as bpf_cgroup_from_id() can be called from any BPF programs including e.g. the ones that attach to functions which are holding the scheduler rq lock. Consider the following BPF program: SEC("fentry/__set_cpus_allowed_ptr_locked") int BPF_PROG(__set_cpus_allowed_ptr_locked, struct task_struct *p, struct affinity_context *affn_ctx, struct rq *rq, struct rq_flags *rf) { struct cgroup *cgrp = bpf_cgroup_from_id(p->cgroups->dfl_cgrp->kn->id); if (cgrp) { bpf_printk("%d[%s] in %s", p->pid, p->comm, cgrp->kn->name); bpf_cgroup_release(cgrp); } return 0; } __set_cpus_allowed_ptr_locked() is called with rq lock held and the above BPF program calls bpf_cgroup_from_id() within leading to the following lockdep warning: ===================================================== WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected 6.7.0-rc3-work-00053-g07124366a1d7-dirty #147 Not tainted ----------------------------------------------------- repro/1620 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: ffffffff833b3688 (kernfs_idr_lock){+.+.}-{2:2}, at: kernfs_find_and_get_node_by_id+0x1e/0x70 and this task is already holding: ffff888237ced698 (&rq->__lock){-.-.}-{2:2}, at: task_rq_lock+0x4e/0xf0 which would create a new lock dependency: (&rq->__lock){-.-.}-{2:2} -> (kernfs_idr_lock){+.+.}-{2:2} ... Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(kernfs_idr_lock); local_irq_disable(); lock(&rq->__lock); lock(kernfs_idr_lock); <Interrupt> lock(&rq->__lock); *** DEADLOCK *** ... Call Trace: dump_stack_lvl+0x55/0x70 dump_stack+0x10/0x20 __lock_acquire+0x781/0x2a40 lock_acquire+0xbf/0x1f0 _raw_spin_lock+0x2f/0x40 kernfs_find_and_get_node_by_id+0x1e/0x70 cgroup_get_from_id+0x21/0x240 bpf_cgroup_from_id+0xe/0x20 bpf_prog_98652316e9337a5a___set_cpus_allowed_ptr_locked+0x96/0x11a bpf_trampoline_6442545632+0x4f/0x1000 __set_cpus_allowed_ptr_locked+0x5/0x5a0 sched_setaffinity+0x1b3/0x290 __x64_sys_sched_setaffinity+0x4f/0x60 do_syscall_64+0x40/0xe0 entry_SYSCALL_64_after_hwframe+0x46/0x4e Let's fix it by protecting kernfs_node and kernfs_root with RCU and making kernfs_find_and_get_node_by_id() acquire rcu_read_lock() instead of kernfs_idr_lock. This adds an rcu_head to kernfs_node making it larger by 16 bytes on 64bit. Combined with the preceding rearrange patch, the net increase is 8 bytes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrea Righi <andrea.righi@canonical.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Link: https://lore.kernel.org/r/20240109214828.252092-4-tj@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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...makes use of the onemessage interface that is available with 3.6.y
See issue 141.