[PATCH][next] drm/nouveau: chan: Avoid -Wflex-array-member-not-at-end warnings

Gustavo A. R. Silva
2025-04-03T16:45:21Z

-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.

Use the `DEFINE_RAW_FLEX()` helper for a few on-stack definitions
of a flexible structure where the size of the flexible-array member
is known at compile-time, and refactor the rest of the code,
accordingly.

So, with these changes, fix the following warnings:

drivers/gpu/drm/nouveau/nouveau_chan.c:274:37: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
drivers/gpu/drm/nouveau/nouveau_chan.c:371:46: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
drivers/gpu/drm/nouveau/nouveau_chan.c:524:42: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/gpu/drm/nouveau/nouveau_chan.c | 115 ++++++++++++-------------
1 file changed, 56 insertions(+), 59 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_chan.c b/drivers/gpu/drm/nouveau/nouveau_chan.c
index cd659b9fd1d9..a7e70517b7cd 100644
--- a/drivers/gpu/drm/nouveau/nouveau_chan.c
+++ b/drivers/gpu/drm/nouveau/nouveau_chan.c
@@ -270,10 +270,7 @@ nouveau_channel_ctor(struct nouveau_cli *cli, bool priv, u64 runm,
{ NV03_CHANNEL_DMA , 0 },
{}
};
- struct {
- struct nvif_chan_v0 chan;
- char name[TASK_COMM_LEN+16];
- } args;
+ DEFINE_RAW_FLEX(struct nvif_chan_v0, args, name, TASK_COMM_LEN + 16);
struct nvif_device *device = &cli->device;
struct nouveau_channel *chan;
const u64 plength = 0x10000;
@@ -298,28 +295,28 @@ nouveau_channel_ctor(struct nouveau_cli *cli, bool priv, u64 runm,
return ret;

/* create channel object */
- args.chan.version = 0;
- args.chan.namelen = sizeof(args.name);
- args.chan.runlist = __ffs64(runm);
- args.chan.runq = 0;
- args.chan.priv = priv;
- args.chan.devm = BIT(0);
+ args->version = 0;
+ args->namelen = __struct_size(args) - sizeof(*args);
+ args->runlist = __ffs64(runm);
+ args->runq = 0;
+ args->priv = priv;
+ args->devm = BIT(0);
if (hosts[cid].oclass < NV50_CHANNEL_GPFIFO) {
- args.chan.vmm = 0;
- args.chan.ctxdma = nvif_handle(&chan->push.ctxdma);
- args.chan.offset = chan->push.addr;
- args.chan.length = 0;
+ args->vmm = 0;
+ args->ctxdma = nvif_handle(&chan->push.ctxdma);
+ args->offset = chan->push.addr;
+ args->length = 0;
} else {
- args.chan.vmm = nvif_handle(&chan->vmm->vmm.object);
+ args->vmm = nvif_handle(&chan->vmm->vmm.object);
if (hosts[cid].oclass < FERMI_CHANNEL_GPFIFO)
- args.chan.ctxdma = nvif_handle(&chan->push.ctxdma);
+ args->ctxdma = nvif_handle(&chan->push.ctxdma);
else
- args.chan.ctxdma = 0;
- args.chan.offset = ioffset + chan->push.addr;
- args.chan.length = ilength;
+ args->ctxdma = 0;
+ args->offset = ioffset + chan->push.addr;
+ args->length = ilength;
}
- args.chan.huserd = 0;
- args.chan.ouserd = 0;
+ args->huserd = 0;
+ args->ouserd = 0;

/* allocate userd */
if (hosts[cid].oclass >= VOLTA_CHANNEL_GPFIFO_A) {
@@ -329,27 +326,28 @@ nouveau_channel_ctor(struct nouveau_cli *cli, bool priv, u64 runm,
if (ret)
return ret;

- args.chan.huserd = nvif_handle(&chan->mem_userd.object);
- args.chan.ouserd = 0;
+ args->huserd = nvif_handle(&chan->mem_userd.object);
+ args->ouserd = 0;

chan->userd = &chan->mem_userd.object;
} else {
chan->userd = &chan->user;
}

- snprintf(args.name, sizeof(args.name), "%s[%d]", current->comm, task_pid_nr(current));
+ snprintf(args->name, __struct_size(args) - sizeof(*args), "%s[%d]",
+ current->comm, task_pid_nr(current));

ret = nvif_object_ctor(&device->object, "abi16ChanUser", 0, hosts[cid].oclass,
- &args, sizeof(args), &chan->user);
+ args, __struct_size(args), &chan->user);
if (ret) {
nouveau_channel_del(pchan);
return ret;
}

- chan->runlist = args.chan.runlist;
- chan->chid = args.chan.chid;
- chan->inst = args.chan.inst;
- chan->token = args.chan.token;
+ chan->runlist = args->runlist;
+ chan->chid = args->chid;
+ chan->inst = args->inst;
+ chan->token = args->token;
return 0;
}

@@ -367,17 +365,17 @@ nouveau_channel_init(struct nouveau_channel *chan, u32 vram, u32 gart)
return ret;

if (chan->user.oclass >= FERMI_CHANNEL_GPFIFO) {
- struct {
- struct nvif_event_v0 base;
- struct nvif_chan_event_v0 host;
- } args;
+ DEFINE_RAW_FLEX(struct nvif_event_v0, args, data,
+ sizeof(struct nvif_chan_event_v0));
+ struct nvif_chan_event_v0 *host =
+ (struct nvif_chan_event_v0 *)args->data;

- args.host.version = 0;
- args.host.type = NVIF_CHAN_EVENT_V0_KILLED;
+ host->version = 0;
+ host->type = NVIF_CHAN_EVENT_V0_KILLED;

ret = nvif_event_ctor(&chan->user, "abi16ChanKilled", chan->chid,
nouveau_channel_killed, false,
- &args.base, sizeof(args), &chan->kill);
+ args, __struct_size(args), &chan->kill);
if (ret == 0)
ret = nvif_event_allow(&chan->kill);
if (ret) {
@@ -520,46 +518,45 @@ nouveau_channels_fini(struct nouveau_drm *drm)
int
nouveau_channels_init(struct nouveau_drm *drm)
{
- struct {
- struct nv_device_info_v1 m;
- struct {
- struct nv_device_info_v1_data channels;
- struct nv_device_info_v1_data runlists;
- } v;
- } args = {
- .m.version = 1,
- .m.count = sizeof(args.v) / sizeof(args.v.channels),
- .v.channels.mthd = NV_DEVICE_HOST_CHANNELS,
- .v.runlists.mthd = NV_DEVICE_HOST_RUNLISTS,
- };
+ DEFINE_RAW_FLEX(struct nv_device_info_v1, args, data, 2);
+ struct nv_device_info_v1_data *channels = &args->data[0];
+ struct nv_device_info_v1_data *runlists = &args->data[1];
struct nvif_object *device = &drm->client.device.object;
int ret, i;

- ret = nvif_object_mthd(device, NV_DEVICE_V0_INFO, &args, sizeof(args));
+ args->version = 1;
+ args->count = (__struct_size(args) - sizeof(*args)) /
+ sizeof(*args->data);
+ channels->mthd = NV_DEVICE_HOST_CHANNELS;
+ runlists->mthd = NV_DEVICE_HOST_RUNLISTS;
+
+ ret = nvif_object_mthd(device, NV_DEVICE_V0_INFO, args,
+ __struct_size(args));
if (ret ||
- args.v.runlists.mthd == NV_DEVICE_INFO_INVALID || !args.v.runlists.data ||
- args.v.channels.mthd == NV_DEVICE_INFO_INVALID)
+ runlists->mthd == NV_DEVICE_INFO_INVALID || !runlists->data ||
+ channels->mthd == NV_DEVICE_INFO_INVALID)
return -ENODEV;

- drm->chan_nr = drm->chan_total = args.v.channels.data;
- drm->runl_nr = fls64(args.v.runlists.data);
+ drm->chan_nr = drm->chan_total = channels->data;
+ drm->runl_nr = fls64(runlists->data);
drm->runl = kcalloc(drm->runl_nr, sizeof(*drm->runl), GFP_KERNEL);
if (!drm->runl)
return -ENOMEM;

if (drm->chan_nr == 0) {
for (i = 0; i < drm->runl_nr; i++) {
- if (!(args.v.runlists.data & BIT(i)))
+ if (!(runlists->data & BIT(i)))
continue;

- args.v.channels.mthd = NV_DEVICE_HOST_RUNLIST_CHANNELS;
- args.v.channels.data = i;
+ channels->mthd = NV_DEVICE_HOST_RUNLIST_CHANNELS;
+ channels->data = i;

- ret = nvif_object_mthd(device, NV_DEVICE_V0_INFO, &args, sizeof(args));
- if (ret || args.v.channels.mthd == NV_DEVICE_INFO_INVALID)
+ ret = nvif_object_mthd(device, NV_DEVICE_V0_INFO, args,
+ __struct_size(args));
+ if (ret || channels->mthd == NV_DEVICE_INFO_INVALID)
return -ENODEV;

- drm->runl[i].chan_nr = args.v.channels.data;
+ drm->runl[i].chan_nr = channels->data;
drm->runl[i].chan_id_base = drm->chan_total;
drm->runl[i].context_base = dma_fence_context_alloc(drm->runl[i].chan_nr);

--
2.43.0