Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

> Sorry for the delayed response, as i was waiting for test results. > I have uploaded the new patch v1 as per your suggestions and result > looks good. Thanks for all the testing. This looks good to me too. Alan

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

> Sorry for the delayed response, as i was waiting for test results. > I have uploaded the new patch v1 as per your suggestions and result > looks good. Thanks for all the testing. This looks good to me too. Alan

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On 1/6/2018 1:20 PM, Kohli, Gaurav wrote: On 1/6/2018 2:35 AM, Alan Cox wrote: On Sat, 6 Jan 2018 01:54:36 +0530 "Kohli, Gaurav" wrote: Hi Alan, Sorry correcting the typo here: +retval =  tty_ldisc_lock(tty, 5 * HZ); +if (retval) +     goto err_release_lock;

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On 1/6/2018 1:20 PM, Kohli, Gaurav wrote: On 1/6/2018 2:35 AM, Alan Cox wrote: On Sat, 6 Jan 2018 01:54:36 +0530 "Kohli, Gaurav" wrote: Hi Alan, Sorry correcting the typo here: +retval =  tty_ldisc_lock(tty, 5 * HZ); +if (retval) +     goto err_release_lock; tty->port->itty = tty; /* *

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On 1/6/2018 2:35 AM, Alan Cox wrote: On Sat, 6 Jan 2018 01:54:36 +0530 "Kohli, Gaurav" wrote: Hi Alan, Sorry correcting the typo here: +retval =  tty_ldisc_lock(tty, 5 * HZ); +if (retval) +     goto err_release_lock; tty->port->itty = tty; /* * Structures all

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On 1/6/2018 2:35 AM, Alan Cox wrote: On Sat, 6 Jan 2018 01:54:36 +0530 "Kohli, Gaurav" wrote: Hi Alan, Sorry correcting the typo here: +retval =  tty_ldisc_lock(tty, 5 * HZ); +if (retval) +     goto err_release_lock; tty->port->itty = tty; /* * Structures all installed ... call the

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On Sat, 6 Jan 2018 01:54:36 +0530 "Kohli, Gaurav" wrote: > Hi Alan, > > Sorry correcting the typo here: > +retval =  tty_ldisc_lock(tty, 5 * HZ); > +if (retval) > +     goto err_release_lock; > tty->port->itty = tty; > /* > * Structures all installed ... call the

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On Sat, 6 Jan 2018 01:54:36 +0530 "Kohli, Gaurav" wrote: > Hi Alan, > > Sorry correcting the typo here: > +retval =  tty_ldisc_lock(tty, 5 * HZ); > +if (retval) > +     goto err_release_lock; > tty->port->itty = tty; > /* > * Structures all installed ... call the ldisc open routines. > * If

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

HI Alan, Sorry correcting the typo here: On 1/6/2018 1:44 AM, Kohli, Gaurav wrote: Hi Alan, On 1/5/2018 7:45 PM, Alan Cox wrote: But in above case , there we can hit another race, if we have a sequence like this tty_init_dev->alloc_tty_struct -> tty_ldisc_init -> this will initialize

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

HI Alan, Sorry correcting the typo here: On 1/6/2018 1:44 AM, Kohli, Gaurav wrote: Hi Alan, On 1/5/2018 7:45 PM, Alan Cox wrote: But in above case , there we can hit another race, if we have a sequence like this tty_init_dev->alloc_tty_struct -> tty_ldisc_init -> this will initialize

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

Hi Alan, Sorry correcting the typo here: +retval =  tty_ldisc_lock(tty, 5 * HZ); +if (retval) +     goto err_release_lock; tty->port->itty = tty; /* * Structures all installed ... call the ldisc open routines. * If we fail here just call release_tty to clean up.  No need * to decrement the

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

Hi Alan, Sorry correcting the typo here: +retval =  tty_ldisc_lock(tty, 5 * HZ); +if (retval) +     goto err_release_lock; tty->port->itty = tty; /* * Structures all installed ... call the ldisc open routines. * If we fail here just call release_tty to clean up.  No need * to decrement the

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

Hi Alan, On 1/5/2018 7:45 PM, Alan Cox wrote: But in above case , there we can hit another race, if we have a sequence like this tty_init_dev->alloc_tty_struct -> tty_ldisc_init -> this will initialize ldisc , but at this moment disc_data is still NULL And if flush_to_ldisc comes in between,

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

Hi Alan, On 1/5/2018 7:45 PM, Alan Cox wrote: But in above case , there we can hit another race, if we have a sequence like this tty_init_dev->alloc_tty_struct -> tty_ldisc_init -> this will initialize ldisc , but at this moment disc_data is still NULL And if flush_to_ldisc comes in between,

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

> But in above case , there we can hit another race, if we have a sequence > like this > tty_init_dev->alloc_tty_struct -> tty_ldisc_init -> this will initialize > ldisc , > but at this moment disc_data is still NULL > > And if flush_to_ldisc comes in between, it will take ldisc reference and

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

> But in above case , there we can hit another race, if we have a sequence > like this > tty_init_dev->alloc_tty_struct -> tty_ldisc_init -> this will initialize > ldisc , > but at this moment disc_data is still NULL > > And if flush_to_ldisc comes in between, it will take ldisc reference and

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On 1/5/2018 7:06 PM, Alan Cox wrote: On Fri, 5 Jan 2018 13:15:45 +0530 "Kohli, Gaurav" wrote: Hi Alan, Can you make that code available otherwise it's impossible to see what the problem might be.  

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On 1/5/2018 7:06 PM, Alan Cox wrote: On Fri, 5 Jan 2018 13:15:45 +0530 "Kohli, Gaurav" wrote: Hi Alan, Can you make that code available otherwise it's impossible to see what the problem might be.   https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/tty/serial?h=msm-4.9

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On Fri, 5 Jan 2018 13:15:45 +0530 "Kohli, Gaurav" wrote: > Hi Alan, > >>> > >>> Can you make that code available otherwise it's impossible to see > >>> what the problem might be. > > > > >   >

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On Fri, 5 Jan 2018 13:15:45 +0530 "Kohli, Gaurav" wrote: > Hi Alan, > >>> > >>> Can you make that code available otherwise it's impossible to see > >>> what the problem might be. > > > > >   > https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/tty/serial?h=msm-4.9 >  As

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

Hi Alan, Can you make that code available otherwise it's impossible to see what the problem might be.   https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/tty/serial?h=msm-4.9  As discussed , there not seems a problem as we are getting print request even when port seems to

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

Hi Alan, Can you make that code available otherwise it's impossible to see what the problem might be.   https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/tty/serial?h=msm-4.9  As discussed , there not seems a problem as we are getting print request even when port seems to

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On Thu, 4 Jan 2018 19:16:46 +0530 "Kohli, Gaurav" wrote: > > Which tty driver ? serial/msm_serial.c ? > > We are using our internal driver, msm_geni_serial.c Can you make that code available otherwise it's impossible to see what the problem might be. > > > > Ok no

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On Thu, 4 Jan 2018 19:16:46 +0530 "Kohli, Gaurav" wrote: > > Which tty driver ? serial/msm_serial.c ? > > We are using our internal driver, msm_geni_serial.c Can you make that code available otherwise it's impossible to see what the problem might be. > > > > Ok no what I need to see is

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

Which tty driver ? serial/msm_serial.c ? We are using our internal driver, msm_geni_serial.c Ok no what I need to see is a trace of what each CPU is doing at the point you detect the problem. That way we can see what the path that races is. Below is stack trace running by init in our

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

Which tty driver ? serial/msm_serial.c ? We are using our internal driver, msm_geni_serial.c Ok no what I need to see is a trace of what each CPU is doing at the point you detect the problem. That way we can see what the path that races is. Below is stack trace running by init in our

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

> > What does a full (all CPU) trace of the bug look like and what tty driver > > are you using when you capture the trace ? Which tty driver ? serial/msm_serial.c ? > We are using tty for console logging, >     |    tty = 0x477AC880 -> ( >     |  magic = 21505, >     | 

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

> > What does a full (all CPU) trace of the bug look like and what tty driver > > are you using when you capture the trace ? Which tty driver ? serial/msm_serial.c ? > We are using tty for console logging, >     |    tty = 0x477AC880 -> ( >     |  magic = 21505, >     | 

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On Wed, 3 Jan 2018 19:18:52 +0530 Gaurav Kohli wrote: > There can be a race, if receive_buf call comes before > tty initialization completes in n_tty_open and tty->disc_data > may be NULL. This makes no sense. If the race exists then the check you do isn't good enough

Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

On Wed, 3 Jan 2018 19:18:52 +0530 Gaurav Kohli wrote: > There can be a race, if receive_buf call comes before > tty initialization completes in n_tty_open and tty->disc_data > may be NULL. This makes no sense. If the race exists then the check you do isn't good enough because the ldsic dsta

[PATCH] tty: fix data race in n_tty_receive_buf_common

There can be a race, if receive_buf call comes before tty initialization completes in n_tty_open and tty->disc_data may be NULL. CPU0cpu1 000|n_tty_receive_buf_common() n_tty_open()

[PATCH] tty: fix data race in n_tty_receive_buf_common

There can be a race, if receive_buf call comes before tty initialization completes in n_tty_open and tty->disc_data may be NULL. CPU0cpu1 000|n_tty_receive_buf_common() n_tty_open()