diff options
author | Nicholas Piggin <npiggin@gmail.com> | 2018-05-01 00:55:51 +1000 |
---|---|---|
committer | Michael Ellerman <mpe@ellerman.id.au> | 2018-07-24 22:09:57 +1000 |
commit | 17cc1dd4924391b54fb179d0868b89dc96f2ee80 (patch) | |
tree | 18aada7559529c711897037d94b316a6d26cfa63 /arch/powerpc/platforms/powernv/opal.c | |
parent | ac4ac788fdadc6b703ff3322de07dee442e08e1c (diff) | |
download | linux-17cc1dd4924391b54fb179d0868b89dc96f2ee80.tar.bz2 |
powerpc/powernv: implement opal_put_chars_atomic
The RAW console does not need writes to be atomic, so relax
opal_put_chars to be able to do partial writes, and implement an
_atomic variant which does not take a spinlock. This API is used
in xmon, so the less locking that is used, the better chance there
is that a crash can be debugged.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/platforms/powernv/opal.c')
-rw-r--r-- | arch/powerpc/platforms/powernv/opal.c | 37 |
1 files changed, 27 insertions, 10 deletions
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c index cf02e602237a..6405b6f20193 100644 --- a/arch/powerpc/platforms/powernv/opal.c +++ b/arch/powerpc/platforms/powernv/opal.c @@ -344,9 +344,9 @@ int opal_get_chars(uint32_t vtermno, char *buf, int count) return 0; } -int opal_put_chars(uint32_t vtermno, const char *data, int total_len) +static int __opal_put_chars(uint32_t vtermno, const char *data, int total_len, bool atomic) { - unsigned long flags; + unsigned long flags = 0 /* shut up gcc */; int written; __be64 olen; s64 rc; @@ -354,11 +354,8 @@ int opal_put_chars(uint32_t vtermno, const char *data, int total_len) if (!opal.entry) return -ENODEV; - /* We want put_chars to be atomic to avoid mangling of hvsi - * packets. To do that, we first test for room and return - * -EAGAIN if there isn't enough. - */ - spin_lock_irqsave(&opal_write_lock, flags); + if (atomic) + spin_lock_irqsave(&opal_write_lock, flags); rc = opal_console_write_buffer_space(vtermno, &olen); if (rc || be64_to_cpu(olen) < total_len) { /* Closed -> drop characters */ @@ -391,14 +388,18 @@ int opal_put_chars(uint32_t vtermno, const char *data, int total_len) written = be64_to_cpu(olen); if (written < total_len) { - /* Should not happen */ - pr_warn("atomic console write returned partial len=%d written=%d\n", total_len, written); + if (atomic) { + /* Should not happen */ + pr_warn("atomic console write returned partial " + "len=%d written=%d\n", total_len, written); + } if (!written) written = -EAGAIN; } out: - spin_unlock_irqrestore(&opal_write_lock, flags); + if (atomic) + spin_unlock_irqrestore(&opal_write_lock, flags); /* In the -EAGAIN case, callers loop, so we have to flush the console * here in case they have interrupts off (and we don't want to wait @@ -412,6 +413,22 @@ out: return written; } +int opal_put_chars(uint32_t vtermno, const char *data, int total_len) +{ + return __opal_put_chars(vtermno, data, total_len, false); +} + +/* + * opal_put_chars_atomic will not perform partial-writes. Data will be + * atomically written to the terminal or not at all. This is not strictly + * true at the moment because console space can race with OPAL's console + * writes. + */ +int opal_put_chars_atomic(uint32_t vtermno, const char *data, int total_len) +{ + return __opal_put_chars(vtermno, data, total_len, true); +} + int opal_flush_console(uint32_t vtermno) { s64 rc; |