diff mbox series

xhci: Remove dead code in xhci_move_dequeue_past_td()

Message ID 20240524-xhci-deadcode-v1-1-a4453a756e0f@marcan.st
State New
Headers show
Series xhci: Remove dead code in xhci_move_dequeue_past_td() | expand

Commit Message

Hector Martin May 24, 2024, 7:07 a.m. UTC 
This codepath is trivially dead, since the function is never called with
a non-NULL td (the only callsite is immediately preceded by a NULL guard).

Signed-off-by: Hector Martin <marcan@marcan.st>
---
 drivers/usb/host/xhci-ring.c | 19 -------------------
 1 file changed, 19 deletions(-)


---
base-commit: a38297e3fb012ddfa7ce0321a7e5a8daeb1872b6
change-id: 20240524-xhci-deadcode-8bf2ebe7609d

Best regards,

Comments

kernel test robot May 24, 2024, 9:39 a.m. UTC | #1 
Hi Hector,

kernel test robot noticed the following build warnings:

[auto build test WARNING on a38297e3fb012ddfa7ce0321a7e5a8daeb1872b6]

url:    https://github.com/intel-lab-lkp/linux/commits/Hector-Martin/xhci-Remove-dead-code-in-xhci_move_dequeue_past_td/20240524-151544
base:   a38297e3fb012ddfa7ce0321a7e5a8daeb1872b6
patch link:    https://lore.kernel.org/r/20240524-xhci-deadcode-v1-1-a4453a756e0f%40marcan.st
patch subject: [PATCH] xhci: Remove dead code in xhci_move_dequeue_past_td()
config: alpha-allyesconfig (https://download.01.org/0day-ci/archive/20240524/202405241706.h0PyUQfL-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240524/202405241706.h0PyUQfL-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405241706.h0PyUQfL-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/usb/host/xhci-ring.c: In function 'xhci_move_dequeue_past_td':
>> drivers/usb/host/xhci-ring.c:695:1: warning: label 'deq_found' defined but not used [-Wunused-label]
     695 | deq_found:
         | ^~~~~~~~~


vim +/deq_found +695 drivers/usb/host/xhci-ring.c

e6b20121c6d5d1 Mathias Nyman 2017-06-02  633  
d1dbfb942c33bf Mathias Nyman 2021-01-29  634  static int xhci_move_dequeue_past_td(struct xhci_hcd *xhci,
d1dbfb942c33bf Mathias Nyman 2021-01-29  635  				unsigned int slot_id, unsigned int ep_index,
d1dbfb942c33bf Mathias Nyman 2021-01-29  636  				unsigned int stream_id, struct xhci_td *td)
d1dbfb942c33bf Mathias Nyman 2021-01-29  637  {
d1dbfb942c33bf Mathias Nyman 2021-01-29  638  	struct xhci_virt_device *dev = xhci->devs[slot_id];
d1dbfb942c33bf Mathias Nyman 2021-01-29  639  	struct xhci_virt_ep *ep = &dev->eps[ep_index];
d1dbfb942c33bf Mathias Nyman 2021-01-29  640  	struct xhci_ring *ep_ring;
d1dbfb942c33bf Mathias Nyman 2021-01-29  641  	struct xhci_command *cmd;
d1dbfb942c33bf Mathias Nyman 2021-01-29  642  	struct xhci_segment *new_seg;
d1dbfb942c33bf Mathias Nyman 2021-01-29  643  	union xhci_trb *new_deq;
d1dbfb942c33bf Mathias Nyman 2021-01-29  644  	int new_cycle;
d1dbfb942c33bf Mathias Nyman 2021-01-29  645  	dma_addr_t addr;
d1dbfb942c33bf Mathias Nyman 2021-01-29  646  	u64 hw_dequeue;
d1dbfb942c33bf Mathias Nyman 2021-01-29  647  	bool cycle_found = false;
d1dbfb942c33bf Mathias Nyman 2021-01-29  648  	bool td_last_trb_found = false;
d1dbfb942c33bf Mathias Nyman 2021-01-29  649  	u32 trb_sct = 0;
d1dbfb942c33bf Mathias Nyman 2021-01-29  650  	int ret;
d1dbfb942c33bf Mathias Nyman 2021-01-29  651  
d1dbfb942c33bf Mathias Nyman 2021-01-29  652  	ep_ring = xhci_triad_to_transfer_ring(xhci, slot_id,
d1dbfb942c33bf Mathias Nyman 2021-01-29  653  			ep_index, stream_id);
d1dbfb942c33bf Mathias Nyman 2021-01-29  654  	if (!ep_ring) {
d1dbfb942c33bf Mathias Nyman 2021-01-29  655  		xhci_warn(xhci, "WARN can't find new dequeue, invalid stream ID %u\n",
d1dbfb942c33bf Mathias Nyman 2021-01-29  656  			  stream_id);
d1dbfb942c33bf Mathias Nyman 2021-01-29  657  		return -ENODEV;
d1dbfb942c33bf Mathias Nyman 2021-01-29  658  	}
d1dbfb942c33bf Mathias Nyman 2021-01-29  659  
d1dbfb942c33bf Mathias Nyman 2021-01-29  660  	hw_dequeue = xhci_get_hw_deq(xhci, dev, ep_index, stream_id);
d1dbfb942c33bf Mathias Nyman 2021-01-29  661  	new_seg = ep_ring->deq_seg;
d1dbfb942c33bf Mathias Nyman 2021-01-29  662  	new_deq = ep_ring->dequeue;
d1dbfb942c33bf Mathias Nyman 2021-01-29  663  	new_cycle = hw_dequeue & 0x1;
d1dbfb942c33bf Mathias Nyman 2021-01-29  664  
d1dbfb942c33bf Mathias Nyman 2021-01-29  665  	/*
d1dbfb942c33bf Mathias Nyman 2021-01-29  666  	 * We want to find the pointer, segment and cycle state of the new trb
d1dbfb942c33bf Mathias Nyman 2021-01-29  667  	 * (the one after current TD's last_trb). We know the cycle state at
d1dbfb942c33bf Mathias Nyman 2021-01-29  668  	 * hw_dequeue, so walk the ring until both hw_dequeue and last_trb are
d1dbfb942c33bf Mathias Nyman 2021-01-29  669  	 * found.
d1dbfb942c33bf Mathias Nyman 2021-01-29  670  	 */
d1dbfb942c33bf Mathias Nyman 2021-01-29  671  	do {
d1dbfb942c33bf Mathias Nyman 2021-01-29  672  		if (!cycle_found && xhci_trb_virt_to_dma(new_seg, new_deq)
d1dbfb942c33bf Mathias Nyman 2021-01-29  673  		    == (dma_addr_t)(hw_dequeue & ~0xf)) {
d1dbfb942c33bf Mathias Nyman 2021-01-29  674  			cycle_found = true;
d1dbfb942c33bf Mathias Nyman 2021-01-29  675  			if (td_last_trb_found)
d1dbfb942c33bf Mathias Nyman 2021-01-29  676  				break;
d1dbfb942c33bf Mathias Nyman 2021-01-29  677  		}
d1dbfb942c33bf Mathias Nyman 2021-01-29  678  		if (new_deq == td->last_trb)
d1dbfb942c33bf Mathias Nyman 2021-01-29  679  			td_last_trb_found = true;
d1dbfb942c33bf Mathias Nyman 2021-01-29  680  
d1dbfb942c33bf Mathias Nyman 2021-01-29  681  		if (cycle_found && trb_is_link(new_deq) &&
d1dbfb942c33bf Mathias Nyman 2021-01-29  682  		    link_trb_toggles_cycle(new_deq))
d1dbfb942c33bf Mathias Nyman 2021-01-29  683  			new_cycle ^= 0x1;
d1dbfb942c33bf Mathias Nyman 2021-01-29  684  
d1dbfb942c33bf Mathias Nyman 2021-01-29  685  		next_trb(xhci, ep_ring, &new_seg, &new_deq);
d1dbfb942c33bf Mathias Nyman 2021-01-29  686  
d1dbfb942c33bf Mathias Nyman 2021-01-29  687  		/* Search wrapped around, bail out */
d1dbfb942c33bf Mathias Nyman 2021-01-29  688  		if (new_deq == ep->ring->dequeue) {
d1dbfb942c33bf Mathias Nyman 2021-01-29  689  			xhci_err(xhci, "Error: Failed finding new dequeue state\n");
d1dbfb942c33bf Mathias Nyman 2021-01-29  690  			return -EINVAL;
d1dbfb942c33bf Mathias Nyman 2021-01-29  691  		}
d1dbfb942c33bf Mathias Nyman 2021-01-29  692  
d1dbfb942c33bf Mathias Nyman 2021-01-29  693  	} while (!cycle_found || !td_last_trb_found);
d1dbfb942c33bf Mathias Nyman 2021-01-29  694  
d1dbfb942c33bf Mathias Nyman 2021-01-29 @695  deq_found:
d1dbfb942c33bf Mathias Nyman 2021-01-29  696  
d1dbfb942c33bf Mathias Nyman 2021-01-29  697  	/* Don't update the ring cycle state for the producer (us). */
d1dbfb942c33bf Mathias Nyman 2021-01-29  698  	addr = xhci_trb_virt_to_dma(new_seg, new_deq);
d1dbfb942c33bf Mathias Nyman 2021-01-29  699  	if (addr == 0) {
d1dbfb942c33bf Mathias Nyman 2021-01-29  700  		xhci_warn(xhci, "Can't find dma of new dequeue ptr\n");
d1dbfb942c33bf Mathias Nyman 2021-01-29  701  		xhci_warn(xhci, "deq seg = %p, deq ptr = %p\n", new_seg, new_deq);
d1dbfb942c33bf Mathias Nyman 2021-01-29  702  		return -EINVAL;
d1dbfb942c33bf Mathias Nyman 2021-01-29  703  	}
d1dbfb942c33bf Mathias Nyman 2021-01-29  704  
d1dbfb942c33bf Mathias Nyman 2021-01-29  705  	if ((ep->ep_state & SET_DEQ_PENDING)) {
d1dbfb942c33bf Mathias Nyman 2021-01-29  706  		xhci_warn(xhci, "Set TR Deq already pending, don't submit for 0x%pad\n",
d1dbfb942c33bf Mathias Nyman 2021-01-29  707  			  &addr);
d1dbfb942c33bf Mathias Nyman 2021-01-29  708  		return -EBUSY;
d1dbfb942c33bf Mathias Nyman 2021-01-29  709  	}
d1dbfb942c33bf Mathias Nyman 2021-01-29  710  
d1dbfb942c33bf Mathias Nyman 2021-01-29  711  	/* This function gets called from contexts where it cannot sleep */
d1dbfb942c33bf Mathias Nyman 2021-01-29  712  	cmd = xhci_alloc_command(xhci, false, GFP_ATOMIC);
d1dbfb942c33bf Mathias Nyman 2021-01-29  713  	if (!cmd) {
d1dbfb942c33bf Mathias Nyman 2021-01-29  714  		xhci_warn(xhci, "Can't alloc Set TR Deq cmd 0x%pad\n", &addr);
d1dbfb942c33bf Mathias Nyman 2021-01-29  715  		return -ENOMEM;
d1dbfb942c33bf Mathias Nyman 2021-01-29  716  	}
d1dbfb942c33bf Mathias Nyman 2021-01-29  717  
d1dbfb942c33bf Mathias Nyman 2021-01-29  718  	if (stream_id)
d1dbfb942c33bf Mathias Nyman 2021-01-29  719  		trb_sct = SCT_FOR_TRB(SCT_PRI_TR);
d1dbfb942c33bf Mathias Nyman 2021-01-29  720  	ret = queue_command(xhci, cmd,
d1dbfb942c33bf Mathias Nyman 2021-01-29  721  		lower_32_bits(addr) | trb_sct | new_cycle,
d1dbfb942c33bf Mathias Nyman 2021-01-29  722  		upper_32_bits(addr),
d1dbfb942c33bf Mathias Nyman 2021-01-29  723  		STREAM_ID_FOR_TRB(stream_id), SLOT_ID_FOR_TRB(slot_id) |
d1dbfb942c33bf Mathias Nyman 2021-01-29  724  		EP_ID_FOR_TRB(ep_index) | TRB_TYPE(TRB_SET_DEQ), false);
d1dbfb942c33bf Mathias Nyman 2021-01-29  725  	if (ret < 0) {
d1dbfb942c33bf Mathias Nyman 2021-01-29  726  		xhci_free_command(xhci, cmd);
d1dbfb942c33bf Mathias Nyman 2021-01-29  727  		return ret;
d1dbfb942c33bf Mathias Nyman 2021-01-29  728  	}
d1dbfb942c33bf Mathias Nyman 2021-01-29  729  	ep->queued_deq_seg = new_seg;
d1dbfb942c33bf Mathias Nyman 2021-01-29  730  	ep->queued_deq_ptr = new_deq;
d1dbfb942c33bf Mathias Nyman 2021-01-29  731  
d1dbfb942c33bf Mathias Nyman 2021-01-29  732  	xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
d1dbfb942c33bf Mathias Nyman 2021-01-29  733  		       "Set TR Deq ptr 0x%llx, cycle %u\n", addr, new_cycle);
d1dbfb942c33bf Mathias Nyman 2021-01-29  734  
d1dbfb942c33bf Mathias Nyman 2021-01-29  735  	/* Stop the TD queueing code from ringing the doorbell until
d1dbfb942c33bf Mathias Nyman 2021-01-29  736  	 * this command completes.  The HC won't set the dequeue pointer
d1dbfb942c33bf Mathias Nyman 2021-01-29  737  	 * if the ring is running, and ringing the doorbell starts the
d1dbfb942c33bf Mathias Nyman 2021-01-29  738  	 * ring running.
d1dbfb942c33bf Mathias Nyman 2021-01-29  739  	 */
d1dbfb942c33bf Mathias Nyman 2021-01-29  740  	ep->ep_state |= SET_DEQ_PENDING;
d1dbfb942c33bf Mathias Nyman 2021-01-29  741  	xhci_ring_cmd_db(xhci);
d1dbfb942c33bf Mathias Nyman 2021-01-29  742  	return 0;
d1dbfb942c33bf Mathias Nyman 2021-01-29  743  }
d1dbfb942c33bf Mathias Nyman 2021-01-29  744
diff mbox series

Patch

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 575f0fd9c9f1..f1ed728d9f8c 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -656,25 +656,6 @@  static int xhci_move_dequeue_past_td(struct xhci_hcd *xhci,
 			  stream_id);
 		return -ENODEV;
 	}
-	/*
-	 * A cancelled TD can complete with a stall if HW cached the trb.
-	 * In this case driver can't find td, but if the ring is empty we
-	 * can move the dequeue pointer to the current enqueue position.
-	 * We shouldn't hit this anymore as cached cancelled TRBs are given back
-	 * after clearing the cache, but be on the safe side and keep it anyway
-	 */
-	if (!td) {
-		if (list_empty(&ep_ring->td_list)) {
-			new_seg = ep_ring->enq_seg;
-			new_deq = ep_ring->enqueue;
-			new_cycle = ep_ring->cycle_state;
-			xhci_dbg(xhci, "ep ring empty, Set new dequeue = enqueue");
-			goto deq_found;
-		} else {
-			xhci_warn(xhci, "Can't find new dequeue state, missing td\n");
-			return -EINVAL;
-		}
-	}
 
 	hw_dequeue = xhci_get_hw_deq(xhci, dev, ep_index, stream_id);
 	new_seg = ep_ring->deq_seg;