Subject: Re: [PATCH] qrtr: Convert qrtr_ports from IDR to XArray

From: Bjorn Andersson <[email-masked]>
Date: Tue, 30 Mar 2021 17:28:58 -0500

On Tue 30 Mar 13:04 CDT 2021, Manivannan Sadhasivam wrote:

> On Fri, Jun 05, 2020 at 05:00:37AM -0700, Matthew Wilcox wrote:
> > From: "Matthew Wilcox (Oracle)" <[email-masked]>
> > 
> > The XArray interface is easier for this driver to use.  Also fixes a
> > bug reported by the improper use of GFP_ATOMIC.
> > 
> > Signed-off-by: Matthew Wilcox (Oracle) <[email-masked]>
> 
> Patch looks good to me. Can you please rebase it on top of netdev or
> v5.12-rc2 and resend?
> 

I asked Jay from Qualcomm to do this a few days ago, so we should
hopefully see this on the list shortly.

Regards,
Bjorn

> Thanks,
> Mani
> 
> > ---
> >  net/qrtr/qrtr.c | 39 +++++++++++++--------------------------
> >  1 file changed, 13 insertions(+), 26 deletions(-)
> > 
> > diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
> > index 2d8d6131bc5f..488f8f326ee5 100644
> > --- a/net/qrtr/qrtr.c
> > +++ b/net/qrtr/qrtr.c
> > @@ -20,6 +20,7 @@
> >  /* auto-bind range */
> >  #define QRTR_MIN_EPH_SOCKET 0x4000
> >  #define QRTR_MAX_EPH_SOCKET 0x7fff
> > +#define QRTR_PORT_RANGE	XA_LIMIT(QRTR_MIN_EPH_SOCKET, QRTR_MAX_EPH_SOCKET)
> >  
> >  /**
> >   * struct qrtr_hdr_v1 - (I|R)PCrouter packet header version 1
> > @@ -106,8 +107,7 @@ static LIST_HEAD(qrtr_all_nodes);
> >  static DEFINE_MUTEX(qrtr_node_lock);
> >  
> >  /* local port allocation management */
> > -static DEFINE_IDR(qrtr_ports);
> > -static DEFINE_MUTEX(qrtr_port_lock);
> > +static DEFINE_XARRAY_ALLOC(qrtr_ports);
> >  
> >  /**
> >   * struct qrtr_node - endpoint node
> > @@ -623,7 +623,7 @@ static struct qrtr_sock *qrtr_port_lookup(int port)
> >  		port = 0;
> >  
> >  	rcu_read_lock();
> > -	ipc = idr_find(&qrtr_ports, port);
> > +	ipc = xa_load(&qrtr_ports, port);
> >  	if (ipc)
> >  		sock_hold(&ipc->sk);
> >  	rcu_read_unlock();
> > @@ -665,9 +665,7 @@ static void qrtr_port_remove(struct qrtr_sock *ipc)
> >  
> >  	__sock_put(&ipc->sk);
> >  
> > -	mutex_lock(&qrtr_port_lock);
> > -	idr_remove(&qrtr_ports, port);
> > -	mutex_unlock(&qrtr_port_lock);
> > +	xa_erase(&qrtr_ports, port);
> >  
> >  	/* Ensure that if qrtr_port_lookup() did enter the RCU read section we
> >  	 * wait for it to up increment the refcount */
> > @@ -688,25 +686,18 @@ static int qrtr_port_assign(struct qrtr_sock *ipc, int *port)
> >  {
> >  	int rc;
> >  
> > -	mutex_lock(&qrtr_port_lock);
> >  	if (!*port) {
> > -		rc = idr_alloc(&qrtr_ports, ipc,
> > -			       QRTR_MIN_EPH_SOCKET, QRTR_MAX_EPH_SOCKET + 1,
> > -			       GFP_ATOMIC);
> > -		if (rc >= 0)
> > -			*port = rc;
> > +		rc = xa_alloc(&qrtr_ports, port, ipc, QRTR_PORT_RANGE,
> > +				GFP_KERNEL);
> >  	} else if (*port < QRTR_MIN_EPH_SOCKET && !capable(CAP_NET_ADMIN)) {
> >  		rc = -EACCES;
> >  	} else if (*port == QRTR_PORT_CTRL) {
> > -		rc = idr_alloc(&qrtr_ports, ipc, 0, 1, GFP_ATOMIC);
> > +		rc = xa_insert(&qrtr_ports, 0, ipc, GFP_KERNEL);
> >  	} else {
> > -		rc = idr_alloc(&qrtr_ports, ipc, *port, *port + 1, GFP_ATOMIC);
> > -		if (rc >= 0)
> > -			*port = rc;
> > +		rc = xa_insert(&qrtr_ports, *port, ipc, GFP_KERNEL);
> >  	}
> > -	mutex_unlock(&qrtr_port_lock);
> >  
> > -	if (rc == -ENOSPC)
> > +	if (rc == -EBUSY)
> >  		return -EADDRINUSE;
> >  	else if (rc < 0)
> >  		return rc;
> > @@ -720,20 +711,16 @@ static int qrtr_port_assign(struct qrtr_sock *ipc, int *port)
> >  static void qrtr_reset_ports(void)
> >  {
> >  	struct qrtr_sock *ipc;
> > -	int id;
> > -
> > -	mutex_lock(&qrtr_port_lock);
> > -	idr_for_each_entry(&qrtr_ports, ipc, id) {
> > -		/* Don't reset control port */
> > -		if (id == 0)
> > -			continue;
> > +	unsigned long index;
> >  
> > +	rcu_read_lock();
> > +	xa_for_each_start(&qrtr_ports, index, ipc, 1) {
> >  		sock_hold(&ipc->sk);
> >  		ipc->sk.sk_err = ENETRESET;
> >  		ipc->sk.sk_error_report(&ipc->sk);
> >  		sock_put(&ipc->sk);
> >  	}
> > -	mutex_unlock(&qrtr_port_lock);
> > +	rcu_read_unlock();
> >  }
> >  
> >  /* Bind socket to address.
> > -- 
> > 2.26.2
> >