| Message ID | 1487364165-21882-1-git-send-email-jan.dakinevich@gmail.com (mailing list archive) |
|---|---|
| State | Rejected |
| Headers | show |
On Fri, Feb 17, 2017 at 11:42:45PM +0300, Jan Dakinevich wrote: > The buffer is used by virtio console driver as DMA buffer. Since v4.9 > (if VMAP_STACK is enabled) we shouldn't use the stack for DMA. You shouldn't use 'static' data either, that's not always guaranteed to be DMA-able, right? > > Signed-off-by: Jan Dakinevich <jan.dakinevich@gmail.com> > --- > drivers/tty/hvc/hvc_console.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c > index 9b5c0fb..1ce6aaf 100644 > --- a/drivers/tty/hvc/hvc_console.c > +++ b/drivers/tty/hvc/hvc_console.c > @@ -143,10 +143,15 @@ static struct hvc_struct *hvc_get_by_index(int index) > static void hvc_console_print(struct console *co, const char *b, > unsigned count) > { > - char c[N_OUTBUF] __ALIGNED__; > unsigned i = 0, n = 0; > int r, donecr = 0, index = co->index; > > + /* > + * Access to the buffer is serialized by console_sem in caller code from > + * kernel/printk/printk.c > + */ > + static char c[N_OUTBUF] __ALIGNED__; What about allocating it dynamically? That's the correct thing to do. thanks, greg k-h
> You shouldn't use 'static' data either, that's not always guaranteed to > be DMA-able, right? I naively thought all 'static' data was linked into .data and the section was always kmapped. > What about allocating it dynamically? That's the correct thing to do. Yep, the solution was more welcomed and happened earlier: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c4baad50297d84bde1a7ad45e50c73adae4a2192 On 03/17/2017 08:09 AM, Greg Kroah-Hartman wrote: > On Fri, Feb 17, 2017 at 11:42:45PM +0300, Jan Dakinevich wrote: >> The buffer is used by virtio console driver as DMA buffer. Since v4.9 >> (if VMAP_STACK is enabled) we shouldn't use the stack for DMA. > > You shouldn't use 'static' data either, that's not always guaranteed to > be DMA-able, right? > >> >> Signed-off-by: Jan Dakinevich <jan.dakinevich@gmail.com> >> --- >> drivers/tty/hvc/hvc_console.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c >> index 9b5c0fb..1ce6aaf 100644 >> --- a/drivers/tty/hvc/hvc_console.c >> +++ b/drivers/tty/hvc/hvc_console.c >> @@ -143,10 +143,15 @@ static struct hvc_struct *hvc_get_by_index(int index) >> static void hvc_console_print(struct console *co, const char *b, >> unsigned count) >> { >> - char c[N_OUTBUF] __ALIGNED__; >> unsigned i = 0, n = 0; >> int r, donecr = 0, index = co->index; >> >> + /* >> + * Access to the buffer is serialized by console_sem in caller code from >> + * kernel/printk/printk.c >> + */ >> + static char c[N_OUTBUF] __ALIGNED__; > > What about allocating it dynamically? That's the correct thing to do. > > thanks, > > greg k-h >
diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c index 9b5c0fb..1ce6aaf 100644 --- a/drivers/tty/hvc/hvc_console.c +++ b/drivers/tty/hvc/hvc_console.c @@ -143,10 +143,15 @@ static struct hvc_struct *hvc_get_by_index(int index) static void hvc_console_print(struct console *co, const char *b, unsigned count) { - char c[N_OUTBUF] __ALIGNED__; unsigned i = 0, n = 0; int r, donecr = 0, index = co->index; + /* + * Access to the buffer is serialized by console_sem in caller code from + * kernel/printk/printk.c + */ + static char c[N_OUTBUF] __ALIGNED__; + /* Console access attempt outside of acceptable console range. */ if (index >= MAX_NR_HVC_CONSOLES) return;
The buffer is used by virtio console driver as DMA buffer. Since v4.9 (if VMAP_STACK is enabled) we shouldn't use the stack for DMA. Signed-off-by: Jan Dakinevich <jan.dakinevich@gmail.com> --- drivers/tty/hvc/hvc_console.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)