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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2009-03-09 10:36:15 -0400
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2009-03-10 19:44:26 -0400
commit187cfc439f7b1a7c91ff72d561b2a7c9c0b83431 (patch)
treef75cc9c96af4efad5071c5d95a49e013248a07b3
parentd301a9f3ffc93b45744535e0b60fb9d6f6825773 (diff)
hvc_console: Remove tty->low_latency on pseries backends
The hvcs and hvsi backends both set tty->low_latency to one, along with more or less scary comments regarding bugs or races that would happen if not doing so. However, they also both call tty_flip_buffer_push() in conexts where it's illegal to do so since some recent tty changes (or at least it may have been illegal always but it nows blows) when low_latency is set (ie, hard interrupt or with spinlock held and irqs disabled). This removes the setting for now to get them back to working condition, we'll have to address the races described in the comments separately if they are still an issue (some of this might have been fixed already). Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r--drivers/char/hvcs.c9
-rw-r--r--drivers/char/hvsi.c1
2 files changed, 0 insertions, 10 deletions
diff --git a/drivers/char/hvcs.c b/drivers/char/hvcs.c
index 6e6eb445d374..c76bccf5354d 100644
--- a/drivers/char/hvcs.c
+++ b/drivers/char/hvcs.c
@@ -1139,15 +1139,6 @@ static int hvcs_open(struct tty_struct *tty, struct file *filp)
1139 hvcsd->tty = tty; 1139 hvcsd->tty = tty;
1140 tty->driver_data = hvcsd; 1140 tty->driver_data = hvcsd;
1141 1141
1142 /*
1143 * Set this driver to low latency so that we actually have a chance at
1144 * catching a throttled TTY after we flip_buffer_push. Otherwise the
1145 * flush_to_async may not execute until after the kernel_thread has
1146 * yielded and resumed the next flip_buffer_push resulting in data
1147 * loss.
1148 */
1149 tty->low_latency = 1;
1150
1151 memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN); 1142 memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1152 1143
1153 /* 1144 /*
diff --git a/drivers/char/hvsi.c b/drivers/char/hvsi.c
index 406f8742a260..2989056a9e39 100644
--- a/drivers/char/hvsi.c
+++ b/drivers/char/hvsi.c
@@ -810,7 +810,6 @@ static int hvsi_open(struct tty_struct *tty, struct file *filp)
810 hp = &hvsi_ports[line]; 810 hp = &hvsi_ports[line];
811 811
812 tty->driver_data = hp; 812 tty->driver_data = hp;
813 tty->low_latency = 1; /* avoid throttle/tty_flip_buffer_push race */
814 813
815 mb(); 814 mb();
816 if (hp->state == HVSI_FSP_DIED) 815 if (hp->state == HVSI_FSP_DIED)