Messages in this thread | | | Subject | Re: [PATCH 4.19 262/276] media: saa7146: avoid high stack usage with clang | From | Hans Verkuil <> | Date | Thu, 6 Jun 2019 13:47:53 +0200 |
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On 6/6/19 1:44 PM, Pavel Machek wrote: > Hi! > >> Two saa7146/hexium files contain a construct that causes a warning >> when built with clang: >> >> drivers/media/pci/saa7146/hexium_orion.c:210:12: error: stack frame size of 2272 bytes in function 'hexium_probe' >> [-Werror,-Wframe-larger-than=] >> static int hexium_probe(struct saa7146_dev *dev) >> ^ >> drivers/media/pci/saa7146/hexium_gemini.c:257:12: error: stack frame size of 2304 bytes in function 'hexium_attach' >> [-Werror,-Wframe-larger-than=] >> static int hexium_attach(struct saa7146_dev *dev, struct saa7146_pci_extension_data *info) >> ^ >> >> This one happens regardless of KASAN, and the problem is that a >> constructor to initialize a dynamically allocated structure leads >> to a copy of that structure on the stack, whereas gcc initializes >> it in place. >> >> Link: https://bugs.llvm.org/show_bug.cgi?id=40776 > >> --- a/drivers/media/pci/saa7146/hexium_gemini.c >> +++ b/drivers/media/pci/saa7146/hexium_gemini.c >> @@ -270,9 +270,8 @@ static int hexium_attach(struct saa7146_dev *dev, struct saa7146_pci_extension_d >> /* enable i2c-port pins */ >> saa7146_write(dev, MC1, (MASK_08 | MASK_24 | MASK_10 | MASK_26)); >> >> - hexium->i2c_adapter = (struct i2c_adapter) { >> - .name = "hexium gemini", >> - }; >> + strscpy(hexium->i2c_adapter.name, "hexium gemini", >> + sizeof(hexium->i2c_adapter.name)); >> saa7146_i2c_adapter_prepare(dev, &hexium->i2c_adapter, SAA7146_I2C_BUS_BIT_RATE_480); >> if (i2c_add_adapter(&hexium->i2c_adapter) < 0) { >> DEB_S("cannot register i2c-device. skipping.\n"); > > As a sideeffect, this removes zero-initialization from > hexium->i2c_adapter. > > Is that intended / correct?
It's correct, the hexium struct that contains the i2c_adapter is zeroed with kzalloc, so there is no need to zero it again.
Regards,
Hans
> > [I tried looked at saa7146_i2c_adapter_prepare(), and that does not > initialize all the fields, either.] > > Best regards, > Pavel >
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