| Message ID | 51ef854f77779c82010379420139993e12c38776.1671898144.git.drv@mailo.com |
|---|---|
| State | New |
| Headers | show |
| Series | tty: serial: dz: convert atomic_* to refcount_* | expand |
On 26. 12. 22, 7:21, Deepak R Varma wrote: > The refcount_* APIs are designed to address known issues with the > atomic_t APIs for reference counting. They provide following distinct > advantages: > - protect the reference counters from overflow/underflow > - avoid use-after-free errors > - provide improved memory ordering guarantee schemes > - neater and safer. > Hence, replace the atomic_* APIs by their equivalent refcount_t > API functions. > > This patch proposal address the following warnings generated by > the atomic_as_refcounter.cocci coccinelle script > atomic_add_return(-1, ...) ... > --- a/drivers/tty/serial/dz.c > +++ b/drivers/tty/serial/dz.c ... > @@ -400,18 +399,16 @@ static int dz_startup(struct uart_port *uport) > struct dz_port *dport = to_dport(uport); > struct dz_mux *mux = dport->mux; > unsigned long flags; > - int irq_guard; > int ret; > u16 tmp; > > - irq_guard = atomic_add_return(1, &mux->irq_guard); > - if (irq_guard != 1) > + refcount_inc(&mux->irq_guard); > + if (refcount_read(&mux->irq_guard) != 1) > return 0; > > - ret = request_irq(dport->port.irq, dz_interrupt, > - IRQF_SHARED, "dz", mux); > + ret = request_irq(dport->port.irq, dz_interrupt, IRQF_SHARED, "dz", mux); How is this related to the above described change?
On Tue, Jan 03, 2023 at 10:00:48AM +0100, Jiri Slaby wrote: > On 26. 12. 22, 7:21, Deepak R Varma wrote: > > The refcount_* APIs are designed to address known issues with the > > atomic_t APIs for reference counting. They provide following distinct > > advantages: > > - protect the reference counters from overflow/underflow > > - avoid use-after-free errors > > - provide improved memory ordering guarantee schemes > > - neater and safer. > > Hence, replace the atomic_* APIs by their equivalent refcount_t > > API functions. > > > > This patch proposal address the following warnings generated by > > the atomic_as_refcounter.cocci coccinelle script > > atomic_add_return(-1, ...) > ... > > --- a/drivers/tty/serial/dz.c > > +++ b/drivers/tty/serial/dz.c > ... > > @@ -400,18 +399,16 @@ static int dz_startup(struct uart_port *uport) > > struct dz_port *dport = to_dport(uport); > > struct dz_mux *mux = dport->mux; > > unsigned long flags; > > - int irq_guard; > > int ret; > > u16 tmp; > > > > - irq_guard = atomic_add_return(1, &mux->irq_guard); > > - if (irq_guard != 1) > > + refcount_inc(&mux->irq_guard); > > + if (refcount_read(&mux->irq_guard) != 1) > > return 0; > > > > - ret = request_irq(dport->port.irq, dz_interrupt, > > - IRQF_SHARED, "dz", mux); > > + ret = request_irq(dport->port.irq, dz_interrupt, IRQF_SHARED, "dz", mux); > > How is this related to the above described change? No, it is not. My apologies. I must have joined the lines for improved readability and forgot to revert. I will restore this in next revision based on the feedback on the other patch of this series. OR I can include this change in the current change log as a "while at it..." statement. Would you advise me? Thank you, ./drv > > -- > js > suse labs >
On Tue, Jan 03, 2023 at 03:39:17PM +0530, Deepak R Varma wrote: > On Tue, Jan 03, 2023 at 10:00:48AM +0100, Jiri Slaby wrote: > > On 26. 12. 22, 7:21, Deepak R Varma wrote: > > > The refcount_* APIs are designed to address known issues with the > > > atomic_t APIs for reference counting. They provide following distinct > > > advantages: > > > - protect the reference counters from overflow/underflow > > > - avoid use-after-free errors > > > - provide improved memory ordering guarantee schemes > > > - neater and safer. > > > Hence, replace the atomic_* APIs by their equivalent refcount_t > > > API functions. > > > > > > This patch proposal address the following warnings generated by > > > the atomic_as_refcounter.cocci coccinelle script > > > atomic_add_return(-1, ...) > > ... > > > --- a/drivers/tty/serial/dz.c > > > +++ b/drivers/tty/serial/dz.c > > ... > > > @@ -400,18 +399,16 @@ static int dz_startup(struct uart_port *uport) > > > struct dz_port *dport = to_dport(uport); > > > struct dz_mux *mux = dport->mux; > > > unsigned long flags; > > > - int irq_guard; > > > int ret; > > > u16 tmp; > > > > > > - irq_guard = atomic_add_return(1, &mux->irq_guard); > > > - if (irq_guard != 1) > > > + refcount_inc(&mux->irq_guard); > > > + if (refcount_read(&mux->irq_guard) != 1) > > > return 0; > > > > > > - ret = request_irq(dport->port.irq, dz_interrupt, > > > - IRQF_SHARED, "dz", mux); > > > + ret = request_irq(dport->port.irq, dz_interrupt, IRQF_SHARED, "dz", mux); > > > > How is this related to the above described change? > > No, it is not. My apologies. I must have joined the lines for improved readability > and forgot to revert. I will restore this in next revision based on the feedback > on the other patch of this series. OR I can include this change in the current > change log as a "while at it..." statement. Would you advise me? NEVER have a "while at it..." change as part of a commit unless it is relevant to the main change being made. You know better... thanks, greg k-h
diff --git a/drivers/tty/serial/dz.c b/drivers/tty/serial/dz.c index b70edc248f8b..0aa59a9beeb7 100644 --- a/drivers/tty/serial/dz.c +++ b/drivers/tty/serial/dz.c @@ -46,7 +46,6 @@ #include <linux/tty.h> #include <linux/tty_flip.h> -#include <linux/atomic.h> #include <linux/refcount.h> #include <linux/io.h> #include <asm/bootinfo.h> @@ -77,7 +76,7 @@ struct dz_port { struct dz_mux { struct dz_port dport[DZ_NB_PORT]; refcount_t map_guard; - atomic_t irq_guard; + refcount_t irq_guard; int initialised; }; @@ -400,18 +399,16 @@ static int dz_startup(struct uart_port *uport) struct dz_port *dport = to_dport(uport); struct dz_mux *mux = dport->mux; unsigned long flags; - int irq_guard; int ret; u16 tmp; - irq_guard = atomic_add_return(1, &mux->irq_guard); - if (irq_guard != 1) + refcount_inc(&mux->irq_guard); + if (refcount_read(&mux->irq_guard) != 1) return 0; - ret = request_irq(dport->port.irq, dz_interrupt, - IRQF_SHARED, "dz", mux); + ret = request_irq(dport->port.irq, dz_interrupt, IRQF_SHARED, "dz", mux); if (ret) { - atomic_add(-1, &mux->irq_guard); + refcount_dec(&mux->irq_guard); printk(KERN_ERR "dz: Cannot get IRQ %d!\n", dport->port.irq); return ret; } @@ -441,15 +438,13 @@ static void dz_shutdown(struct uart_port *uport) struct dz_port *dport = to_dport(uport); struct dz_mux *mux = dport->mux; unsigned long flags; - int irq_guard; u16 tmp; spin_lock_irqsave(&dport->port.lock, flags); dz_stop_tx(&dport->port); spin_unlock_irqrestore(&dport->port.lock, flags); - irq_guard = atomic_add_return(-1, &mux->irq_guard); - if (!irq_guard) { + if (refcount_dec_and_test(&mux->irq_guard)) { /* Disable interrupts. */ tmp = dz_in(dport, DZ_CSR); tmp &= ~(DZ_RIE | DZ_TIE);
The refcount_* APIs are designed to address known issues with the atomic_t APIs for reference counting. They provide following distinct advantages: - protect the reference counters from overflow/underflow - avoid use-after-free errors - provide improved memory ordering guarantee schemes - neater and safer. Hence, replace the atomic_* APIs by their equivalent refcount_t API functions. This patch proposal address the following warnings generated by the atomic_as_refcounter.cocci coccinelle script atomic_add_return(-1, ...) Signed-off-by: Deepak R Varma <drv@mailo.com> --- Please Note: 1. The patch is compile tested using dec_station.defconfig for MIPS architecture. 2. This patch should be applied after patch 1/2 of this series due to dependency. Changes in v3: 1. Include the individual patches in a series and highlight dependency. Feedback provided by gregkh@linuxfoundation.org Changes in v2: 1. Separate the combined change into one variable per patch as suggested by gregkh@linuxfoundation.org drivers/tty/serial/dz.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) -- 2.34.1