| Message ID | 20210514214422.3019105-1-nathanl@linux.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | powerpc/udbg_hvc: retry putc on -EAGAIN | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (b68d19e1abdbafef9481c7c0b0bcaff34d7af17d) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | warning | total: 1 errors, 0 warnings, 0 checks, 8 lines checked |
| snowpatch_ozlabs/needsstable | success | Patch has no Fixes tags |
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 <nathanl@linux.ibm.com> > --- > 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
Greg KH <gregkh@linuxfoundation.org> 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 <nathanl@linux.ibm.com> >> --- >> 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
On Sun, May 23, 2021 at 08:51:09PM +1000, Michael Ellerman wrote: > Greg KH <gregkh@linuxfoundation.org> 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 <nathanl@linux.ibm.com> > >> --- > >> 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
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
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)
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 <nathanl@linux.ibm.com> --- drivers/tty/hvc/hvc_vio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)