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| author | Cássio Gabriel <cassiogabrielcontato@gmail.com> | 2026-06-01 04:23:35 +0300 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2026-06-01 12:29:02 +0300 |
| commit | e9c82f767f0f46ef90eeefccc0a8006cc86aff40 (patch) | |
| tree | 0f2a30dfa45fb67d68a28817ed91b82cf79155c6 | |
| parent | 8a2d0b5496850403d1105efbbe54aa8fc68cae6f (diff) | |
| download | linux-e9c82f767f0f46ef90eeefccc0a8006cc86aff40.tar.xz | |
ALSA: core: Use flexible array for card private data
snd_card_new() and snd_devm_card_new() allocate struct snd_card
together with optional driver-private storage. The storage is currently
described only by open-coded sizeof(*card) + extra_size arithmetic, and
snd_card_init() reaches it by manually adding sizeof(struct snd_card) to
the card pointer.
Make the trailing storage explicit with a flexible array member. Use
kzalloc_flex() for the regular allocation path and struct_size() for the
devres allocation size. This documents the layout and avoids open-coded
variable-size object arithmetic.
Align the flexible array to unsigned long long so the driver-private area
does not become less aligned than the old sizeof(struct snd_card) tail
address on 32-bit ABIs.
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260531-alsa-card-private-flex-array-v2-1-e4ff67f5bd23@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
| -rw-r--r-- | include/sound/core.h | 2 | ||||
| -rw-r--r-- | sound/core/init.c | 7 |
2 files changed, 6 insertions, 3 deletions
diff --git a/include/sound/core.h b/include/sound/core.h index 4093ec82a0a1..4bb76c21c956 100644 --- a/include/sound/core.h +++ b/include/sound/core.h @@ -148,6 +148,8 @@ struct snd_card { struct snd_mixer_oss *mixer_oss; int mixer_oss_change_count; #endif + + unsigned char private_data_area[] __aligned(__alignof__(unsigned long long)); }; #define dev_to_snd_card(p) container_of(p, struct snd_card, card_dev) diff --git a/sound/core/init.c b/sound/core/init.c index 0c316189e947..2408160b8ea1 100644 --- a/sound/core/init.c +++ b/sound/core/init.c @@ -181,7 +181,7 @@ int snd_card_new(struct device *parent, int idx, const char *xid, if (extra_size < 0) extra_size = 0; - card = kzalloc(sizeof(*card) + extra_size, GFP_KERNEL); + card = kzalloc_flex(*card, private_data_area, extra_size); if (!card) return -ENOMEM; @@ -232,7 +232,8 @@ int snd_devm_card_new(struct device *parent, int idx, const char *xid, int err; *card_ret = NULL; - card = devres_alloc(__snd_card_release, sizeof(*card) + extra_size, + card = devres_alloc(__snd_card_release, + struct_size(card, private_data_area, extra_size), GFP_KERNEL); if (!card) return -ENOMEM; @@ -280,7 +281,7 @@ static int snd_card_init(struct snd_card *card, struct device *parent, int err; if (extra_size > 0) - card->private_data = (char *)card + sizeof(struct snd_card); + card->private_data = card->private_data_area; if (xid) strscpy(card->id, xid, sizeof(card->id)); err = 0; |