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SubjectRE: [EXTERNAL] [PATCH net-next] net: fec: Convert fec driver to use lock guards
Date
> -----Original Message-----
> From: Suman Ghosh <sumang@marvell.com>
> Sent: 2024年5月7日 19:55
> To: Wei Fang <wei.fang@nxp.com>; davem@davemloft.net;
> edumazet@google.com; kuba@kernel.org; pabeni@redhat.com; Shenwei
> Wang <shenwei.wang@nxp.com>; Clark Wang <xiaoning.wang@nxp.com>;
> richardcochran@gmail.com; netdev@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org; imx@lists.linux.dev
> Subject: RE: [EXTERNAL] [PATCH net-next] net: fec: Convert fec driver to use
> lock guards
>
> > drivers/net/ethernet/freescale/fec_main.c | 37 ++++----
> >drivers/net/ethernet/freescale/fec_ptp.c | 104 +++++++++-------------
> > 2 files changed, 58 insertions(+), 83 deletions(-)
> >
> >diff --git a/drivers/net/ethernet/freescale/fec_main.c
> >b/drivers/net/ethernet/freescale/fec_main.c
> >index 8bd213da8fb6..5f98c0615115 100644
> >--- a/drivers/net/ethernet/freescale/fec_main.c
> >+++ b/drivers/net/ethernet/freescale/fec_main.c
> >@@ -1397,12 +1397,11 @@ static void
> > fec_enet_hwtstamp(struct fec_enet_private *fep, unsigned ts,
> > struct skb_shared_hwtstamps *hwtstamps) {
> >- unsigned long flags;
> > u64 ns;
> >
> >- spin_lock_irqsave(&fep->tmreg_lock, flags);
> >- ns = timecounter_cyc2time(&fep->tc, ts);
> >- spin_unlock_irqrestore(&fep->tmreg_lock, flags);
> >+ scoped_guard(spinlock_irqsave, &fep->tmreg_lock) {
> >+ ns = timecounter_cyc2time(&fep->tc, ts);
> >+ }
> >
> > memset(hwtstamps, 0, sizeof(*hwtstamps));
> > hwtstamps->hwtstamp = ns_to_ktime(ns); @@ -2313,15 +2312,13 @@
> static
> >int fec_enet_clk_enable(struct net_device *ndev, bool enable)
> > return ret;
> >
> > if (fep->clk_ptp) {
> >- mutex_lock(&fep->ptp_clk_mutex);
> >- ret = clk_prepare_enable(fep->clk_ptp);
> >- if (ret) {
> >- mutex_unlock(&fep->ptp_clk_mutex);
> >- goto failed_clk_ptp;
> >- } else {
> >- fep->ptp_clk_on = true;
> >+ scoped_guard(mutex, &fep->ptp_clk_mutex) {
> >+ ret = clk_prepare_enable(fep->clk_ptp);
> >+ if (ret)
> >+ goto failed_clk_ptp;
> >+ else
> >+ fep->ptp_clk_on = true;
> > }
> >- mutex_unlock(&fep->ptp_clk_mutex);
> > }
> >
> > ret = clk_prepare_enable(fep->clk_ref); @@ -2336,10 +2333,10
> @@
> >static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
> > } else {
> > clk_disable_unprepare(fep->clk_enet_out);
> > if (fep->clk_ptp) {
> >- mutex_lock(&fep->ptp_clk_mutex);
> >- clk_disable_unprepare(fep->clk_ptp);
> >- fep->ptp_clk_on = false;
> >- mutex_unlock(&fep->ptp_clk_mutex);
> >+ scoped_guard(mutex, &fep->ptp_clk_mutex) {
> >+ clk_disable_unprepare(fep->clk_ptp);
> >+ fep->ptp_clk_on = false;
> >+ }
> > }
> > clk_disable_unprepare(fep->clk_ref);
> > clk_disable_unprepare(fep->clk_2x_txclk);
> >@@ -2352,10 +2349,10 @@ static int fec_enet_clk_enable(struct
> net_device
> >*ndev, bool enable)
> > clk_disable_unprepare(fep->clk_ref);
> > failed_clk_ref:
> > if (fep->clk_ptp) {
> >- mutex_lock(&fep->ptp_clk_mutex);
> >- clk_disable_unprepare(fep->clk_ptp);
> >- fep->ptp_clk_on = false;
> >- mutex_unlock(&fep->ptp_clk_mutex);
> >+ scoped_guard(mutex, &fep->ptp_clk_mutex) {
> [Suman] Hi Wei,
> I am new to the use of scoped_guard() and have a confusion here. Above,
> "goto failed_clk_ref" is getting called after scoped_guard() declaration and
> you are again doing scoped_guard() inside the goto label failed_clk_ref. Why
> is this double declaration needed?

The lock will be freed when it goes out of scope. And the second scope_guard() is
not nested in the first scope_guard().

> >+ clk_disable_unprepare(fep->clk_ptp);
> >+ fep->ptp_clk_on = false;
> >+ }
> > }
> > failed_clk_ptp:
> > clk_disable_unprepare(fep->clk_enet_out);

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