[PATCH] usb: xhci: Replace tasklet with work
From: Davidlohr Bueso <dave@stgolabs.net>
Date: 2021-01-19 00:10:58
Also in:
lkml
Subsystem:
the rest, usb subsystem, usb xhci driver · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Mathias Nyman
Tasklets have long been deprecated as being too heavy on the system by running in irq context - and this is not a performance critical path. If a higher priority process wants to run, it must wait for the tasklet to finish before doing so. dbc_rx_push() will now run in process context and have further concurrency - tasklets being serialized among themselves, but this is done holding the port_lock, so it should be fine. Signed-off-by: Davidlohr Bueso <redacted> --- drivers/usb/host/xhci-dbgcap.h | 2 +- drivers/usb/host/xhci-dbgtty.c | 19 +++++++++++-------- 2 files changed, 12 insertions(+), 9 deletions(-)
diff --git a/drivers/usb/host/xhci-dbgcap.h b/drivers/usb/host/xhci-dbgcap.h
index c70b78d504eb..aec66009af51 100644
--- a/drivers/usb/host/xhci-dbgcap.h
+++ b/drivers/usb/host/xhci-dbgcap.h@@ -104,7 +104,7 @@ struct dbc_port { struct list_head read_pool; struct list_head read_queue; unsigned int n_read; - struct tasklet_struct push; + struct work_struct push; struct list_head write_pool; struct kfifo write_fifo;
diff --git a/drivers/usb/host/xhci-dbgtty.c b/drivers/usb/host/xhci-dbgtty.c
index ae4e4ab638b5..50da77d92cf6 100644
--- a/drivers/usb/host/xhci-dbgtty.c
+++ b/drivers/usb/host/xhci-dbgtty.c@@ -108,7 +108,7 @@ dbc_read_complete(struct xhci_dbc *dbc, struct dbc_request *req) spin_lock_irqsave(&port->port_lock, flags); list_add_tail(&req->list_pool, &port->read_queue); - tasklet_schedule(&port->push); + schedule_work(&port->push); spin_unlock_irqrestore(&port->port_lock, flags); }
@@ -272,7 +272,7 @@ static void dbc_tty_unthrottle(struct tty_struct *tty) unsigned long flags; spin_lock_irqsave(&port->port_lock, flags); - tasklet_schedule(&port->push); + schedule_work(&port->push); spin_unlock_irqrestore(&port->port_lock, flags); }
@@ -288,15 +288,18 @@ static const struct tty_operations dbc_tty_ops = { .unthrottle = dbc_tty_unthrottle, }; -static void dbc_rx_push(struct tasklet_struct *t) +static void dbc_rx_push(struct work_struct *work) { struct dbc_request *req; struct tty_struct *tty; unsigned long flags; bool do_push = false; bool disconnect = false; - struct dbc_port *port = from_tasklet(port, t, push); - struct list_head *queue = &port->read_queue; + struct dbc_port *port; + struct list_head *queue; + + port = container_of(work, struct dbc_port, push); + queue = &port->read_queue; spin_lock_irqsave(&port->port_lock, flags); tty = port->port.tty;
@@ -349,7 +352,7 @@ static void dbc_rx_push(struct tasklet_struct *t) if (!list_empty(queue) && tty) { if (!tty_throttled(tty)) { if (do_push) - tasklet_schedule(&port->push); + schedule_work(&port->push); else pr_warn("ttyDBC0: RX not scheduled?\n"); }
@@ -382,7 +385,7 @@ xhci_dbc_tty_init_port(struct xhci_dbc *dbc, struct dbc_port *port) { tty_port_init(&port->port); spin_lock_init(&port->port_lock); - tasklet_setup(&port->push, dbc_rx_push); + INIT_WORK(&port->push, dbc_rx_push); INIT_LIST_HEAD(&port->read_pool); INIT_LIST_HEAD(&port->read_queue); INIT_LIST_HEAD(&port->write_pool);
@@ -394,7 +397,7 @@ xhci_dbc_tty_init_port(struct xhci_dbc *dbc, struct dbc_port *port) static void xhci_dbc_tty_exit_port(struct dbc_port *port) { - tasklet_kill(&port->push); + cancel_work_sync(&port->push); tty_port_destroy(&port->port); }
--
2.26.2