xdp/qede: setup xdp_rxq_info and intro xdp_rxq_info_is_reg

The driver code qede_free_fp_array() depend on kfree() can be called
with a NULL pointer. This stems from the qede_alloc_fp_array()
function which either (kz)alloc memory for fp->txq or fp->rxq.
This also simplifies error handling code in case of memory allocation
failures, but xdp_rxq_info_unreg need to know the difference.

Introduce xdp_rxq_info_is_reg() to handle if a memory allocation fails
and detect this is the failure path by seeing that xdp_rxq_info was
not registred yet, which first happens after successful alloaction in
qede_init_fp().

Driver hook points for xdp_rxq_info:
 * reg  : qede_init_fp
 * unreg: qede_free_fp_array

Tested on actual hardware with samples/bpf program.

V2: Driver have no proper error path for failed XDP RX-queue info reg, as
qede_init_fp() is a void function.

Cc: everest-linux-l2@cavium.com
Cc: Ariel Elior <Ariel.Elior@cavium.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

drivers/net/ethernet/qlogic/qede/qede.h

@@ -40,6 +40,7 @@
 #include <linux/kernel.h>
 #include <linux/mutex.h>
 #include <linux/bpf.h>
+#include <net/xdp.h>
 #include <linux/qed/qede_rdma.h>
 #include <linux/io.h>
 #ifdef CONFIG_RFS_ACCEL
@@ -345,6 +346,7 @@ struct qede_rx_queue {
 	u64 xdp_no_pass;
 
 	void *handle;
+	struct xdp_rxq_info xdp_rxq;
 };
 
 union db_prod {

drivers/net/ethernet/qlogic/qede/qede_fp.c

@@ -1006,6 +1006,7 @@ static bool qede_rx_xdp(struct qede_dev *edev,
 	xdp.data = xdp.data_hard_start + *data_offset;
 	xdp_set_data_meta_invalid(&xdp);
 	xdp.data_end = xdp.data + *len;
+	xdp.rxq = &rxq->xdp_rxq;
 
 	/* Queues always have a full reset currently, so for the time
 	 * being until there's atomic program replace just mark read

drivers/net/ethernet/qlogic/qede/qede_main.c

@@ -765,6 +765,12 @@ static void qede_free_fp_array(struct qede_dev *edev)
 			fp = &edev->fp_array[i];
 
 			kfree(fp->sb_info);
+			/* Handle mem alloc failure case where qede_init_fp
+			 * didn't register xdp_rxq_info yet.
+			 * Implicit only (fp->type & QEDE_FASTPATH_RX)
+			 */
+			if (fp->rxq && xdp_rxq_info_is_reg(&fp->rxq->xdp_rxq))
+				xdp_rxq_info_unreg(&fp->rxq->xdp_rxq);
 			kfree(fp->rxq);
 			kfree(fp->xdp_tx);
 			kfree(fp->txq);
@@ -1493,6 +1499,10 @@ static void qede_init_fp(struct qede_dev *edev)
 			else
 				fp->rxq->data_direction = DMA_FROM_DEVICE;
 			fp->rxq->dev = &edev->pdev->dev;
+
+			/* Driver have no error path from here */
+			WARN_ON(xdp_rxq_info_reg(&fp->rxq->xdp_rxq, edev->ndev,
+						 fp->rxq->rxq_id) < 0);
 		}
 
 		if (fp->type & QEDE_FASTPATH_TX) {

include/net/xdp.h

@@ -43,5 +43,6 @@ int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
 		     struct net_device *dev, u32 queue_index);
 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
 void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
+bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
 
 #endif /* __LINUX_NET_XDP_H__ */

net/core/xdp.c

@@ -65,3 +65,9 @@ void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq)
 	xdp_rxq->reg_state = REG_STATE_UNUSED;
 }
 EXPORT_SYMBOL_GPL(xdp_rxq_info_unused);
+
+bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq)
+{
+	return (xdp_rxq->reg_state == REG_STATE_REGISTERED);
+}
+EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg);