[PATCH 3.17 069/141] drm/radeon: add locking around atombios scratch space usage

Greg Kroah-Hartman
2014-11-19T22:23:49Z

From: Dave Airlie <airlied@redhat.com>

commit 1c9498425453bb65ef339a57705c5ef59fe1541d upstream.

While developing MST support I noticed I often got the wrong data
back from a transaction, in a racy fashion. I noticed the scratch
space wasn't locked against concurrent users.

Based on a patch by Alex, but I've made it a bit more obvious when
things are locked.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/radeon/atom.c | 11 ++++++++++-
drivers/gpu/drm/radeon/atom.h | 2 ++
drivers/gpu/drm/radeon/atombios_dp.c | 4 +++-
drivers/gpu/drm/radeon/atombios_i2c.c | 4 +++-
drivers/gpu/drm/radeon/radeon_device.c | 1 +
5 files changed, 19 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/radeon/atom.c
+++ b/drivers/gpu/drm/radeon/atom.c
@@ -1217,7 +1217,7 @@ free:
return ret;
}

-int atom_execute_table(struct atom_context *ctx, int index, uint32_t * params)
+int atom_execute_table_scratch_unlocked(struct atom_context *ctx, int index, uint32_t * params)
{
int r;

@@ -1238,6 +1238,15 @@ int atom_execute_table(struct atom_conte
return r;
}

+int atom_execute_table(struct atom_context *ctx, int index, uint32_t * params)
+{
+ int r;
+ mutex_lock(&ctx->scratch_mutex);
+ r = atom_execute_table_scratch_unlocked(ctx, index, params);
+ mutex_unlock(&ctx->scratch_mutex);
+ return r;
+}
+
static int atom_iio_len[] = { 1, 2, 3, 3, 3, 3, 4, 4, 4, 3 };

static void atom_index_iio(struct atom_context *ctx, int base)
--- a/drivers/gpu/drm/radeon/atom.h
+++ b/drivers/gpu/drm/radeon/atom.h
@@ -125,6 +125,7 @@ struct card_info {
struct atom_context {
struct card_info *card;
struct mutex mutex;
+ struct mutex scratch_mutex;
void *bios;
uint32_t cmd_table, data_table;
uint16_t *iio;
@@ -145,6 +146,7 @@ extern int atom_debug;

struct atom_context *atom_parse(struct card_info *, void *);
int atom_execute_table(struct atom_context *, int, uint32_t *);
+int atom_execute_table_scratch_unlocked(struct atom_context *, int, uint32_t *);
int atom_asic_init(struct atom_context *);
void atom_destroy(struct atom_context *);
bool atom_parse_data_header(struct atom_context *ctx, int index, uint16_t *size,
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -100,6 +100,7 @@ static int radeon_process_aux_ch(struct
memset(&args, 0, sizeof(args));

mutex_lock(&chan->mutex);
+ mutex_lock(&rdev->mode_info.atom_context->scratch_mutex);

base = (unsigned char *)(rdev->mode_info.atom_context->scratch + 1);

@@ -113,7 +114,7 @@ static int radeon_process_aux_ch(struct
if (ASIC_IS_DCE4(rdev))
args.v2.ucHPD_ID = chan->rec.hpd;

- atom_execute_table(rdev->mode_info.atom_context, index, (uint32_t *)&args);
+ atom_execute_table_scratch_unlocked(rdev->mode_info.atom_context, index, (uint32_t *)&args);

*ack = args.v1.ucReplyStatus;

@@ -147,6 +148,7 @@ static int radeon_process_aux_ch(struct

r = recv_bytes;
done:
+ mutex_unlock(&rdev->mode_info.atom_context->scratch_mutex);
mutex_unlock(&chan->mutex);

return r;
--- a/drivers/gpu/drm/radeon/atombios_i2c.c
+++ b/drivers/gpu/drm/radeon/atombios_i2c.c
@@ -48,6 +48,7 @@ static int radeon_process_i2c_ch(struct
memset(&args, 0, sizeof(args));

mutex_lock(&chan->mutex);
+ mutex_lock(&rdev->mode_info.atom_context->scratch_mutex);

base = (unsigned char *)rdev->mode_info.atom_context->scratch;

@@ -82,7 +83,7 @@ static int radeon_process_i2c_ch(struct
args.ucSlaveAddr = slave_addr << 1;
args.ucLineNumber = chan->rec.i2c_id;

- atom_execute_table(rdev->mode_info.atom_context, index, (uint32_t *)&args);
+ atom_execute_table_scratch_unlocked(rdev->mode_info.atom_context, index, (uint32_t *)&args);

/* error */
if (args.ucStatus != HW_ASSISTED_I2C_STATUS_SUCCESS) {
@@ -95,6 +96,7 @@ static int radeon_process_i2c_ch(struct
radeon_atom_copy_swap(buf, base, num, false);

done:
+ mutex_unlock(&rdev->mode_info.atom_context->scratch_mutex);
mutex_unlock(&chan->mutex);

return r;
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -952,6 +952,7 @@ int radeon_atombios_init(struct radeon_d
}

mutex_init(&rdev->mode_info.atom_context->mutex);
+ mutex_init(&rdev->mode_info.atom_context->scratch_mutex);
radeon_atom_initialize_bios_scratch_regs(rdev->ddev);
atom_allocate_fb_scratch(rdev->mode_info.atom_context);
return 0;