# \[PATCH\] powerpc/udbg\_hvc: retry putc on -EAGAIN - Subsystems: HYPERVISOR VIRTUAL CONSOLE DRIVER, THE REST, TTY LAYER AND SERIAL DRIVERS - Maintainers: Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby - Status: LANDED (027f55e87c30 ยท 2021-05-23 10:51) - Landed in mainline as 027f55e87c30 on 2021-05-23. - List: linuxppc-dev - 5 messages, 4 authors - Page: https://ratatoskr.run/linuxppc-dev/2021/05/1378232/t ## \[PATCH\] powerpc/udbg\_hvc: retry putc on -EAGAIN - From: Nathan Lynch \ - Date: 2021-05-14 21:44:37 - Message: https://ratatoskr.run/linuxppc-dev/2021/05/1378232.md ```text hvterm_raw_put_chars() calls hvc_put_chars(), which may return -EAGAIN when the underlying hcall returns a "busy" status, but udbg_hvc_putc() doesn't handle this. When using xmon on a PowerVM guest, this can result in incomplete or garbled output when printing relatively large amounts of data quickly, such as when dumping the kernel log buffer. Call again on -EAGAIN. Signed-off-by: Nathan Lynch --- drivers/tty/hvc/hvc_vio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/hvc/hvc_vio.c b/drivers/tty/hvc/hvc_vio.c index 798f27f40cc2..76d2a7038095 100644 --- a/drivers/tty/hvc/hvc_vio.c +++ b/drivers/tty/hvc/hvc_vio.c @@ -249,7 +249,7 @@ static void udbg_hvc_putc(char c) count = hvterm_hvsi_put_chars(0, &c, 1); break; } - } while(count == 0); + } while(count == 0 || count == -EAGAIN); } static int udbg_hvc_getc_poll(void) -- 2.30.2 ``` ## Re: \[PATCH\] powerpc/udbg\_hvc: retry putc on -EAGAIN - From: Greg KH \ - Date: 2021-05-21 12:47:45 - Message: https://ratatoskr.run/linuxppc-dev/2021/05/1387462.md ```text On Fri, May 14, 2021 at 04:44:22PM -0500, Nathan Lynch wrote: > hvterm_raw_put_chars() calls hvc_put_chars(), which may return -EAGAIN > when the underlying hcall returns a "busy" status, but udbg_hvc_putc() > doesn't handle this. When using xmon on a PowerVM guest, this can > result in incomplete or garbled output when printing relatively large > amounts of data quickly, such as when dumping the kernel log buffer. > > Call again on -EAGAIN. > > Signed-off-by: Nathan Lynch > --- > drivers/tty/hvc/hvc_vio.c | 2 +- Subject line does not match up with this file name. Don't you want "tty" and "hvc" in there somewhere? thanks, greg k-h ``` ## Re: \[PATCH\] powerpc/udbg\_hvc: retry putc on -EAGAIN - From: Michael Ellerman \ - Date: 2021-05-23 10:51:19 - Message: https://ratatoskr.run/linuxppc-dev/2021/05/1388648.md ```text Greg KH [ref] writes: > On Fri, May 14, 2021 at 04:44:22PM -0500, Nathan Lynch wrote: >> hvterm_raw_put_chars() calls hvc_put_chars(), which may return -EAGAIN >> when the underlying hcall returns a "busy" status, but udbg_hvc_putc() >> doesn't handle this. When using xmon on a PowerVM guest, this can >> result in incomplete or garbled output when printing relatively large >> amounts of data quickly, such as when dumping the kernel log buffer. >> >> Call again on -EAGAIN. >> >> Signed-off-by: Nathan Lynch >> --- >> drivers/tty/hvc/hvc_vio.c | 2 +- > > Subject line does not match up with this file name. > > Don't you want "tty" and "hvc" in there somewhere? It's a powerpc only driver, but I guess the subject should still be "tty: hvc: ..." to match convention. I was planning to take this via the powerpc tree, but I can drop it if you'd rather take it. cheers ``` ## Re: \[PATCH\] powerpc/udbg\_hvc: retry putc on -EAGAIN - From: Greg KH \ - Date: 2021-05-27 11:10:31 - Message: https://ratatoskr.run/linuxppc-dev/2021/05/1393857.md ```text On Sun, May 23, 2021 at 08:51:09PM +1000, Michael Ellerman wrote: > Greg KH [ref] writes: > > On Fri, May 14, 2021 at 04:44:22PM -0500, Nathan Lynch wrote: > >> hvterm_raw_put_chars() calls hvc_put_chars(), which may return -EAGAIN > >> when the underlying hcall returns a "busy" status, but udbg_hvc_putc() > >> doesn't handle this. When using xmon on a PowerVM guest, this can > >> result in incomplete or garbled output when printing relatively large > >> amounts of data quickly, such as when dumping the kernel log buffer. > >> > >> Call again on -EAGAIN. > >> > >> Signed-off-by: Nathan Lynch > >> --- > >> drivers/tty/hvc/hvc_vio.c | 2 +- > > > > Subject line does not match up with this file name. > > > > Don't you want "tty" and "hvc" in there somewhere? > > It's a powerpc only driver, but I guess the subject should still be > "tty: hvc: ..." to match convention. > > I was planning to take this via the powerpc tree, but I can drop it if > you'd rather take it. No problem, feel free to take it yourself! greg k-h ``` ## Re: \[PATCH\] powerpc/udbg\_hvc: retry putc on -EAGAIN - From: Michael Ellerman \ - Date: 2021-06-06 12:13:05 - Message: https://ratatoskr.run/linuxppc-dev/2021/06/1403910.md ```text On Fri, 14 May 2021 16:44:22 -0500, Nathan Lynch wrote: > hvterm_raw_put_chars() calls hvc_put_chars(), which may return -EAGAIN > when the underlying hcall returns a "busy" status, but udbg_hvc_putc() > doesn't handle this. When using xmon on a PowerVM guest, this can > result in incomplete or garbled output when printing relatively large > amounts of data quickly, such as when dumping the kernel log buffer. > > Call again on -EAGAIN. Applied to powerpc/next. [1/1] powerpc/udbg_hvc: retry putc on -EAGAIN https://git.kernel.org/powerpc/c/027f55e87c3094270a3223f7331d033fe15a2b3f cheers ```