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avoid using list_for_each_entry_safe when closing endpoints to prevent potential infinite loop 

list_for_each_entry_safe is only safe when the current entry is being removed.
If other entries in the list could potentially be removed it can result in an infinite loop.

Because usbh_lld_ep_close blocks on each urb during iteration, it may give up its lock on
the system and allow an interrupt to remove a different urb from the list,
resulting in an infinite loop when the thread resumes.
This commit is contained in:
Austin Morton 2017-12-27 05:53:41 -05:00
parent ca79ff2e87
commit 40769f9bd3
1 changed files with 3 additions and 2 deletions
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5
os/hal/ports/STM32/LLD/USBHv1/hal_usbh_lld.c
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@ -594,9 +594,10 @@ void usbh_lld_ep_open(usbh_ep_t *ep) {
} }
void usbh_lld_ep_close(usbh_ep_t *ep) { void usbh_lld_ep_close(usbh_ep_t *ep) {
usbh_urb_t *urb, *tmp; usbh_urb_t *urb;
uinfof("\t%s: Closing EP...", ep->name); uinfof("\t%s: Closing EP...", ep->name);
list_for_each_entry_safe(urb, usbh_urb_t, tmp, &ep->urb_list, node) { while (!list_empty(&ep->urb_list)) {
urb = list_first_entry(&ep->urb_list, usbh_urb_t, node);
uinfof("\t%s: Abort URB, USBH_URBSTATUS_DISCONNECTED", ep->name); uinfof("\t%s: Abort URB, USBH_URBSTATUS_DISCONNECTED", ep->name);
_usbh_urb_abort_and_waitS(urb, USBH_URBSTATUS_DISCONNECTED); _usbh_urb_abort_and_waitS(urb, USBH_URBSTATUS_DISCONNECTED);
} }