On 11/03/2026 00:40, Rosen Penev wrote: > A flexible array member allows one allocation instead of two. Which > means one less kfree to worry about.
Hi Rosen, Thanks for the patch! I agree, doing this as two kzalloc()s makes zero sense (no pun intended). > > Signed-off-by: Rosen Penev <[email protected]> > --- > drivers/gpu/drm/imagination/pvr_fw_trace.c | 21 +++++---------------- > 1 file changed, 5 insertions(+), 16 deletions(-) > > diff --git a/drivers/gpu/drm/imagination/pvr_fw_trace.c > b/drivers/gpu/drm/imagination/pvr_fw_trace.c > index e154cb35f604..caf504f2bf85 100644 > --- a/drivers/gpu/drm/imagination/pvr_fw_trace.c > +++ b/drivers/gpu/drm/imagination/pvr_fw_trace.c > @@ -241,9 +241,6 @@ update_logtype(struct pvr_device *pvr_dev, u32 group_mask) > } > > struct pvr_fw_trace_seq_data { > - /** @buffer: Pointer to copy of trace data. */ > - u32 *buffer; > - > /** @start_offset: Starting offset in trace data, as reported by FW. */ > u32 start_offset; > > @@ -252,6 +249,9 @@ struct pvr_fw_trace_seq_data { > > /** @assert_buf: Trace assert buffer, as reported by FW. */ > struct rogue_fwif_file_info_buf assert_buf; > + > + /** @buffer: Pointer to copy of trace data. */ Can you update this comment? > + u32 buffer[]; > }; > > static u32 find_sfid(u32 id) > @@ -455,17 +455,10 @@ static int fw_trace_open(struct inode *inode, struct > file *file) > struct pvr_fw_trace_seq_data *trace_seq_data; > int err; > > - trace_seq_data = kzalloc_obj(*trace_seq_data); > + trace_seq_data = kzalloc_flex(*trace_seq_data, buffer, > ROGUE_FW_TRACE_BUF_DEFAULT_SIZE_IN_DWORDS); Given the buffer is 48KB, I think it's safe to say kcalloc() was the wrong choice in the first place. The choice of 12,000 for the DEFAULT_SIZE define appears arbitrary, and although other sizes haven't been tested I wonder if a more "efficient" replacement here would be to make it a power-of-2 size and use folio_alloc()/folio_address()/folio_put() for the buffer instead of making it a flexible array member. Or maybe I'm overthinking it and we should just stick with a simple vzalloc(struct_size(...))/vfree(). I'll leave it up to you. Cheers, Matt > if (!trace_seq_data) > return -ENOMEM; > > - trace_seq_data->buffer = > kcalloc(ROGUE_FW_TRACE_BUF_DEFAULT_SIZE_IN_DWORDS, > - sizeof(*trace_seq_data->buffer), > GFP_KERNEL); > - if (!trace_seq_data->buffer) { > - err = -ENOMEM; > - goto err_free_data; > - } > - > /* > * Take a local copy of the trace buffer, as firmware may still be > * writing to it. This will exist as long as this file is open. > @@ -478,15 +471,12 @@ static int fw_trace_open(struct inode *inode, struct > file *file) > > err = seq_open(file, &pvr_fw_trace_seq_ops); > if (err) > - goto err_free_buffer; > + goto err_free_data; > > ((struct seq_file *)file->private_data)->private = trace_seq_data; > > return 0; > > -err_free_buffer: > - kfree(trace_seq_data->buffer); > - > err_free_data: > kfree(trace_seq_data); > > @@ -499,7 +489,6 @@ static int fw_trace_release(struct inode *inode, struct > file *file) > ((struct seq_file *)file->private_data)->private; > > seq_release(inode, file); > - kfree(trace_seq_data->buffer); > kfree(trace_seq_data); > > return 0; -- Matt Coster E: [email protected]
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