Le 04/09/2023 à 19:03, Christophe Leroy a écrit :

Le 04/09/2023 à 14:31, Alexandra Diupina a écrit :

quoted

Process the result of hdlc_open() and call uhdlc_close()
in case of an error. It is necessary to pass the error
code up the control flow, similar to a possible
error in request_irq().
Also add a hdlc_close() call to the uhdlc_close()
because the comment to hdlc_close() says it must be called
by the hardware driver when the HDLC device is being closed

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: c19b6d246a35 ("drivers/net: support hdlc function for QE-UCC")
Signed-off-by: Alexandra Diupina <redacted>
---
v4: undo all the things done prior to hdlc_open() as
Jakub Kicinski [off-list ref] suggested,
add hdlc_close() call to the uhdlc_close() to match the function comment,
add uhdlc_close() declaration to the top of the file not to put the
uhdlc_close() function definition before uhdlc_open()
v3: Fix the commits tree
v2: Remove the 'rc' variable (stores the return value of the
hdlc_open()) as Christophe Leroy [off-list ref] suggested
  drivers/net/wan/fsl_ucc_hdlc.c | 8 +++++++-
  1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wan/fsl_ucc_hdlc.c 

b/drivers/net/wan/fsl_ucc_hdlc.c
index 47c2ad7a3e42..fd999dabdd39 100644

--- a/drivers/net/wan/fsl_ucc_hdlc.c
+++ b/drivers/net/wan/fsl_ucc_hdlc.c

@@ -34,6 +34,8 @@

  #define TDM_PPPOHT_SLIC_MAXIN
  #define RX_BD_ERRORS (R_CD_S | R_OV_S | R_CR_S | R_AB_S | R_NO_S | 
R_LG_S)
+static int uhdlc_close(struct net_device *dev);
+
  static struct ucc_tdm_info utdm_primary_info = {
      .uf_info = {
          .tsa = 0,

@@ -731,7 +733,9 @@ static int uhdlc_open(struct net_device *dev)

          napi_enable(&priv->napi);
          netdev_reset_queue(dev);
          netif_start_queue(dev);
-        hdlc_open(dev);
+
+        int rc = hdlc_open(dev);

Do not mix declarations and code. Please put all declaration at the top 
of the block.

quoted

+        return rc == 0 ? 0 : (uhdlc_close(dev), rc);
      }

That's not easy to read.

I know that's more changes, but I'd prefer something like:

static int uhdlc_open(struct net_device *dev)
{
     u32 cecr_subblock;
     hdlc_device *hdlc = dev_to_hdlc(dev);
     struct ucc_hdlc_private *priv = hdlc->priv;
     struct ucc_tdm *utdm = priv->utdm;
     int rc;

     if (priv->hdlc_busy != 1)

Of course should be:

	if (priv->hdlc_busy == 1)

         return 0;

     if (request_irq(priv->ut_info->uf_info.irq,
             ucc_hdlc_irq_handler, 0, "hdlc", priv))
         return -ENODEV;

     cecr_subblock = ucc_fast_get_qe_cr_subblock(
                 priv->ut_info->uf_info.ucc_num);

     qe_issue_cmd(QE_INIT_TX_RX, cecr_subblock,
              QE_CR_PROTOCOL_UNSPECIFIED, 0);

     ucc_fast_enable(priv->uccf, COMM_DIR_RX | COMM_DIR_TX);

     /* Enable the TDM port */
     if (priv->tsa)
         qe_setbits_8(&utdm->si_regs->siglmr1_h, 0x1 << utdm->tdm_port);

     priv->hdlc_busy = 1;
     netif_device_attach(priv->ndev);
     napi_enable(&priv->napi);
     netdev_reset_queue(dev);
     netif_start_queue(dev);

     rc = hdlc_open(dev);
     if (rc)
         uhdlc_close(dev);

     return rc;
}

quoted

      return 0;

@@ -824,6 +828,8 @@ static int uhdlc_close(struct net_device *dev)

      netdev_reset_queue(dev);
      priv->hdlc_busy = 0;
+    hdlc_close(dev);
+
      return 0;
  }

And while you are looking at the correctness of this code, is it sure 
that uhdlc_open() cannot be called twice in parallele ?
If it can be called in parallèle I think the "if (priv->hdlc_busy != 1)" 
should be replaced by something using cmpxchg()