From 43eaf1b17845a25e3e3a7d3f09c2f5ebd4a9d607 Mon Sep 17 00:00:00 2001 From: Vincent Mailhol Date: Tue, 15 Feb 2022 08:48:14 +0900 Subject: [PATCH] can: gs_usb: change active_channels's type from atomic_t to u8 commit 035b0fcf02707d3c9c2890dc1484b11aa5335eb1 upstream. The driver uses an atomic_t variable: gs_usb:active_channels to keep track of the number of opened channels in order to only allocate memory for the URBs when this count changes from zero to one. However, the driver does not decrement the counter when an error occurs in gs_can_open(). This issue is fixed by changing the type from atomic_t to u8 and by simplifying the logic accordingly. It is safe to use an u8 here because the network stack big kernel lock (a.k.a. rtnl_mutex) is being hold. For details, please refer to [1]. [1] https://lore.kernel.org/linux-can/CAMZ6Rq+sHpiw34ijPsmp7vbUpDtJwvVtdV7CvRZJsLixjAFfrg@mail.gmail.com/T/#t Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices") Link: https://lore.kernel.org/all/20220214234814.1321599-1-mailhol.vincent@wanadoo.fr Signed-off-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- drivers/net/can/usb/gs_usb.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c index 3f759fae81fe2..e023c401f4f77 100644 --- a/drivers/net/can/usb/gs_usb.c +++ b/drivers/net/can/usb/gs_usb.c @@ -190,8 +190,8 @@ struct gs_can { struct gs_usb { struct gs_can *canch[GS_MAX_INTF]; struct usb_anchor rx_submitted; - atomic_t active_channels; struct usb_device *udev; + u8 active_channels; }; /* 'allocate' a tx context. @@ -588,7 +588,7 @@ static int gs_can_open(struct net_device *netdev) if (rc) return rc; - if (atomic_add_return(1, &parent->active_channels) == 1) { + if (!parent->active_channels) { for (i = 0; i < GS_MAX_RX_URBS; i++) { struct urb *urb; u8 *buf; @@ -689,6 +689,7 @@ static int gs_can_open(struct net_device *netdev) dev->can.state = CAN_STATE_ERROR_ACTIVE; + parent->active_channels++; if (!(dev->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)) netif_start_queue(netdev); @@ -704,7 +705,8 @@ static int gs_can_close(struct net_device *netdev) netif_stop_queue(netdev); /* Stop polling */ - if (atomic_dec_and_test(&parent->active_channels)) + parent->active_channels--; + if (!parent->active_channels) usb_kill_anchored_urbs(&parent->rx_submitted); /* Stop sending URBs */ @@ -983,8 +985,6 @@ static int gs_usb_probe(struct usb_interface *intf, init_usb_anchor(&dev->rx_submitted); - atomic_set(&dev->active_channels, 0); - usb_set_intfdata(intf, dev); dev->udev = interface_to_usbdev(intf);