Re: [PATCH] VMCI: Use threaded irqs instead of tasklets

From: Bryan Tan
Date: Tue Jan 03 2023 - 06:52:04 EST

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> On 30 Nov 2022, at 07:05, Vishnu Dasa <vdasa@xxxxxxxxxx> wrote:
>
> From: Vishnu Dasa <vdasa@xxxxxxxxxx>
>
> The vmci_dispatch_dgs() tasklet function calls vmci_read_data()
> which uses wait_event() resulting in invalid sleep in an atomic
> context (and therefore potentially in a deadlock).
>
> Use threaded irqs to fix this issue and completely remove usage
> of tasklets.
>
> [ 20.264639] BUG: sleeping function called from invalid context at drivers/misc/vmw_vmci/vmci_guest.c:145
> [ 20.264643] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 762, name: vmtoolsd
> [ 20.264645] preempt_count: 101, expected: 0
> [ 20.264646] RCU nest depth: 0, expected: 0
> [ 20.264647] 1 lock held by vmtoolsd/762:
> [ 20.264648] #0: ffff0000874ae440 (sk_lock-AF_VSOCK){+.+.}-{0:0}, at: vsock_connect+0x60/0x330 [vsock]
> [ 20.264658] Preemption disabled at:
> [ 20.264659] [<ffff80000151d7d8>] vmci_send_datagram+0x44/0xa0 [vmw_vmci]
> [ 20.264665] CPU: 0 PID: 762 Comm: vmtoolsd Not tainted 5.19.0-0.rc8.20220727git39c3c396f813.60.fc37.aarch64 #1
> [ 20.264667] Hardware name: VMware, Inc. VBSA/VBSA, BIOS VEFI 12/31/2020
> [ 20.264668] Call trace:
> [ 20.264669] dump_backtrace+0xc4/0x130
> [ 20.264672] show_stack+0x24/0x80
> [ 20.264673] dump_stack_lvl+0x88/0xb4
> [ 20.264676] dump_stack+0x18/0x34
> [ 20.264677] __might_resched+0x1a0/0x280
> [ 20.264679] __might_sleep+0x58/0x90
> [ 20.264681] vmci_read_data+0x74/0x120 [vmw_vmci]
> [ 20.264683] vmci_dispatch_dgs+0x64/0x204 [vmw_vmci]
> [ 20.264686] tasklet_action_common.constprop.0+0x13c/0x150
> [ 20.264688] tasklet_action+0x40/0x50
> [ 20.264689] __do_softirq+0x23c/0x6b4
> [ 20.264690] __irq_exit_rcu+0x104/0x214
> [ 20.264691] irq_exit_rcu+0x1c/0x50
> [ 20.264693] el1_interrupt+0x38/0x6c
> [ 20.264695] el1h_64_irq_handler+0x18/0x24
> [ 20.264696] el1h_64_irq+0x68/0x6c
> [ 20.264697] preempt_count_sub+0xa4/0xe0
> [ 20.264698] _raw_spin_unlock_irqrestore+0x64/0xb0
> [ 20.264701] vmci_send_datagram+0x7c/0xa0 [vmw_vmci]
> [ 20.264703] vmci_datagram_dispatch+0x84/0x100 [vmw_vmci]
> [ 20.264706] vmci_datagram_send+0x2c/0x40 [vmw_vmci]
> [ 20.264709] vmci_transport_send_control_pkt+0xb8/0x120 [vmw_vsock_vmci_transport]
> [ 20.264711] vmci_transport_connect+0x40/0x7c [vmw_vsock_vmci_transport]
> [ 20.264713] vsock_connect+0x278/0x330 [vsock]
> [ 20.264715] __sys_connect_file+0x8c/0xc0
> [ 20.264718] __sys_connect+0x84/0xb4
> [ 20.264720] __arm64_sys_connect+0x2c/0x3c
> [ 20.264721] invoke_syscall+0x78/0x100
> [ 20.264723] el0_svc_common.constprop.0+0x68/0x124
> [ 20.264724] do_el0_svc+0x38/0x4c
> [ 20.264725] el0_svc+0x60/0x180
> [ 20.264726] el0t_64_sync_handler+0x11c/0x150
> [ 20.264728] el0t_64_sync+0x190/0x194
>
> Signed-off-by: Vishnu Dasa <vdasa@xxxxxxxxxx>
> Suggested-by: Zack Rusin <zackr@xxxxxxxxxx>
> Reported-by: Nadav Amit <namit@xxxxxxxxxx>
> Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx>
> Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx>
> Fixes: 463713eb6164 ("VMCI: dma dg: add support for DMA datagrams receive")
> Cc: <stable@xxxxxxxxxxxxxxx> # v5.18+
> Cc: VMware PV-Drivers Reviewers <pv-drivers@xxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Bryan Tan <bryantan@xxxxxxxxxx>
> ---
> drivers/misc/vmw_vmci/vmci_guest.c | 49 ++++++++++++------------------
> 1 file changed, 19 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/misc/vmw_vmci/vmci_guest.c b/drivers/misc/vmw_vmci/vmci_guest.c
> index aa7b05de97dd..6ab717b4a5db 100644
> --- a/drivers/misc/vmw_vmci/vmci_guest.c
> +++ b/drivers/misc/vmw_vmci/vmci_guest.c
> @@ -56,8 +56,6 @@ struct vmci_guest_device {
>
> bool exclusive_vectors;
>
> - struct tasklet_struct datagram_tasklet;
> - struct tasklet_struct bm_tasklet;
> struct wait_queue_head inout_wq;
>
> void *data_buffer;
> @@ -304,9 +302,8 @@ static int vmci_check_host_caps(struct pci_dev *pdev)
> * This function assumes that it has exclusive access to the data
> * in register(s) for the duration of the call.
> */
> -static void vmci_dispatch_dgs(unsigned long data)
> +static void vmci_dispatch_dgs(struct vmci_guest_device *vmci_dev)
> {
> - struct vmci_guest_device *vmci_dev = (struct vmci_guest_device *)data;
> u8 *dg_in_buffer = vmci_dev->data_buffer;
> struct vmci_datagram *dg;
> size_t dg_in_buffer_size = VMCI_MAX_DG_SIZE;
> @@ -465,10 +462,8 @@ static void vmci_dispatch_dgs(unsigned long data)
> * Scans the notification bitmap for raised flags, clears them
> * and handles the notifications.
> */
> -static void vmci_process_bitmap(unsigned long data)
> +static void vmci_process_bitmap(struct vmci_guest_device *dev)
> {
> - struct vmci_guest_device *dev = (struct vmci_guest_device *)data;
> -
> if (!dev->notification_bitmap) {
> dev_dbg(dev->dev, "No bitmap present in %s\n", __func__);
> return;
> @@ -486,13 +481,13 @@ static irqreturn_t vmci_interrupt(int irq, void *_dev)
> struct vmci_guest_device *dev = _dev;
>
> /*
> - * If we are using MSI-X with exclusive vectors then we simply schedule
> - * the datagram tasklet, since we know the interrupt was meant for us.
> + * If we are using MSI-X with exclusive vectors then we simply call
> + * vmci_dispatch_dgs(), since we know the interrupt was meant for us.
> * Otherwise we must read the ICR to determine what to do.
> */
>
> if (dev->exclusive_vectors) {
> - tasklet_schedule(&dev->datagram_tasklet);
> + vmci_dispatch_dgs(dev);
> } else {
> unsigned int icr;
>
> @@ -502,12 +497,12 @@ static irqreturn_t vmci_interrupt(int irq, void *_dev)
> return IRQ_NONE;
>
> if (icr & VMCI_ICR_DATAGRAM) {
> - tasklet_schedule(&dev->datagram_tasklet);
> + vmci_dispatch_dgs(dev);
> icr &= ~VMCI_ICR_DATAGRAM;
> }
>
> if (icr & VMCI_ICR_NOTIFICATION) {
> - tasklet_schedule(&dev->bm_tasklet);
> + vmci_process_bitmap(dev);
> icr &= ~VMCI_ICR_NOTIFICATION;
> }
>
> @@ -536,7 +531,7 @@ static irqreturn_t vmci_interrupt_bm(int irq, void *_dev)
> struct vmci_guest_device *dev = _dev;
>
> /* For MSI-X we can just assume it was meant for us. */
> - tasklet_schedule(&dev->bm_tasklet);
> + vmci_process_bitmap(dev);
>
> return IRQ_HANDLED;
> }
> @@ -638,10 +633,6 @@ static int vmci_guest_probe_device(struct pci_dev *pdev,
> vmci_dev->iobase = iobase;
> vmci_dev->mmio_base = mmio_base;
>
> - tasklet_init(&vmci_dev->datagram_tasklet,
> - vmci_dispatch_dgs, (unsigned long)vmci_dev);
> - tasklet_init(&vmci_dev->bm_tasklet,
> - vmci_process_bitmap, (unsigned long)vmci_dev);
> init_waitqueue_head(&vmci_dev->inout_wq);
>
> if (mmio_base != NULL) {
> @@ -808,8 +799,9 @@ static int vmci_guest_probe_device(struct pci_dev *pdev,
> * Request IRQ for legacy or MSI interrupts, or for first
> * MSI-X vector.
> */
> - error = request_irq(pci_irq_vector(pdev, 0), vmci_interrupt,
> - IRQF_SHARED, KBUILD_MODNAME, vmci_dev);
> + error = request_threaded_irq(pci_irq_vector(pdev, 0), NULL,
> + vmci_interrupt, IRQF_SHARED,
> + KBUILD_MODNAME, vmci_dev);
> if (error) {
> dev_err(&pdev->dev, "Irq %u in use: %d\n",
> pci_irq_vector(pdev, 0), error);
> @@ -823,9 +815,9 @@ static int vmci_guest_probe_device(struct pci_dev *pdev,
> * between the vectors.
> */
> if (vmci_dev->exclusive_vectors) {
> - error = request_irq(pci_irq_vector(pdev, 1),
> - vmci_interrupt_bm, 0, KBUILD_MODNAME,
> - vmci_dev);
> + error = request_threaded_irq(pci_irq_vector(pdev, 1), NULL,
> + vmci_interrupt_bm, 0,
> + KBUILD_MODNAME, vmci_dev);
> if (error) {
> dev_err(&pdev->dev,
> "Failed to allocate irq %u: %d\n",
> @@ -833,9 +825,11 @@ static int vmci_guest_probe_device(struct pci_dev *pdev,
> goto err_free_irq;
> }
> if (caps_in_use & VMCI_CAPS_DMA_DATAGRAM) {
> - error = request_irq(pci_irq_vector(pdev, 2),
> - vmci_interrupt_dma_datagram,
> - 0, KBUILD_MODNAME, vmci_dev);
> + error = request_threaded_irq(pci_irq_vector(pdev, 2),
> + NULL,
> + vmci_interrupt_dma_datagram,
> + 0, KBUILD_MODNAME,
> + vmci_dev);
> if (error) {
> dev_err(&pdev->dev,
> "Failed to allocate irq %u: %d\n",
> @@ -871,8 +865,6 @@ static int vmci_guest_probe_device(struct pci_dev *pdev,
>
> err_free_irq:
> free_irq(pci_irq_vector(pdev, 0), vmci_dev);
> - tasklet_kill(&vmci_dev->datagram_tasklet);
> - tasklet_kill(&vmci_dev->bm_tasklet);
>
> err_disable_msi:
> pci_free_irq_vectors(pdev);
> @@ -943,9 +935,6 @@ static void vmci_guest_remove_device(struct pci_dev *pdev)
> free_irq(pci_irq_vector(pdev, 0), vmci_dev);
> pci_free_irq_vectors(pdev);
>
> - tasklet_kill(&vmci_dev->datagram_tasklet);
> - tasklet_kill(&vmci_dev->bm_tasklet);
> -
> if (vmci_dev->notification_bitmap) {
> /*
> * The device reset above cleared the bitmap state of the
> --
> 2.34.1

Reviewed-by: Bryan Tan <bryantan@xxxxxxxxxx>

Next message: AngeloGioacchino Del Regno: "Re: [RFC PATCH 3/4] dt-bindings: panel: Introduce dual-link LVDS panel"
Previous message: Fabio Estevam: "Re: [PATCH] staging: media: imx: remove unnecessary return variable"
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