2008-07-04 13:06:43

by Vitaly Mayatskih

Subject: [PATCH] PowerPC: honor O_NONBLOCK flag for rtas error_log

rtas_log_read() currently doesn't count O_NONBLOCK flag. This sample
code will block on read:

fd = open ("/proc/ppc64/rtas/error_log", O_RDONLY | O_NONBLOCK);
while (1) {
err =read (fd, buf, 4096);
printf("err = %d, errno = %d (%s)\n", err, errno, strerror(errno));
sleep(1);
}

With patched kernel it produces such (correct) output:

err = 2052, errno = 0 (Success)
err = -1, errno = 11 (Resource temporarily unavailable)
err = -1, errno = 11 (Resource temporarily unavailable)
err = -1, errno = 11 (Resource temporarily unavailable)
err = -1, errno = 11 (Resource temporarily unavailable)

Signed-off-by: Vitaly Mayatskikh <[email protected]>

diff --git a/arch/powerpc/platforms/pseries/rtasd.c b/arch/powerpc/platforms/pseries/rtasd.c
index 7d3e2b0..f530f68 100644
--- a/arch/powerpc/platforms/pseries/rtasd.c
+++ b/arch/powerpc/platforms/pseries/rtasd.c
@@ -291,22 +291,25 @@ static ssize_t rtas_log_read(struct file * file, char __user * buf,
if (!access_ok(VERIFY_WRITE, buf, count))
return -EFAULT;

- tmp = kmalloc(count, GFP_KERNEL);
- if (!tmp)
- return -ENOMEM;
-
-
spin_lock_irqsave(&rtasd_log_lock, s);
/* if it's 0, then we know we got the last one (the one in NVRAM) */
- if (rtas_log_size == 0 && logging_enabled)
+ if (rtas_log_size == 0 && logging_enabled) {
nvram_clear_error_log();
+ if (file->f_flags & O_NONBLOCK) {
+ spin_unlock_irqrestore(&rtasd_log_lock, s);
+ return -EAGAIN;
+ }
+ }
spin_unlock_irqrestore(&rtasd_log_lock, s);

-
error = wait_event_interruptible(rtas_log_wait, rtas_log_size);
if (error)
goto out;

+ tmp = kmalloc(count, GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;
+
spin_lock_irqsave(&rtasd_log_lock, s);
offset = rtas_error_log_buffer_max * (rtas_log_start & LOG_NUMBER_MASK);
memcpy(tmp, &rtas_log_buf[offset], count);

--
wbr, Vitaly

2008-07-04 13:12:53

by Vitaly Mayatskih

Subject: Re: [PATCH] PowerPC: honor O_NONBLOCK flag for rtas error_log

Vitaly Mayatskikh <[email protected]> writes:

> rtas_log_read() currently doesn't count O_NONBLOCK flag. This sample
> code will block on read:
>
> fd = open ("/proc/ppc64/rtas/error_log", O_RDONLY | O_NONBLOCK);
> while (1) {
> err =read (fd, buf, 4096);
> printf("err = %d, errno = %d (%s)\n", err, errno, strerror(errno));
> sleep(1);
> }
>
> With patched kernel it produces such (correct) output:
>
> err = 2052, errno = 0 (Success)
> err = -1, errno = 11 (Resource temporarily unavailable)
> err = -1, errno = 11 (Resource temporarily unavailable)
> err = -1, errno = 11 (Resource temporarily unavailable)
> err = -1, errno = 11 (Resource temporarily unavailable)

Sorry, wrong patch :(

Signed-off-by: Vitaly Mayatskikh <[email protected]>

diff --git a/arch/powerpc/platforms/pseries/rtasd.c b/arch/powerpc/platforms/pseries/rtasd.c
index 7d3e2b0..3343211 100644
--- a/arch/powerpc/platforms/pseries/rtasd.c
+++ b/arch/powerpc/platforms/pseries/rtasd.c
@@ -291,21 +291,24 @@ static ssize_t rtas_log_read(struct file * file, char __user * buf,
if (!access_ok(VERIFY_WRITE, buf, count))
return -EFAULT;

- tmp = kmalloc(count, GFP_KERNEL);
- if (!tmp)
- return -ENOMEM;
-
-
spin_lock_irqsave(&rtasd_log_lock, s);
/* if it's 0, then we know we got the last one (the one in NVRAM) */
- if (rtas_log_size == 0 && logging_enabled)
+ if (rtas_log_size == 0 && logging_enabled) {
nvram_clear_error_log();
+ if (file->f_flags & O_NONBLOCK) {
+ spin_unlock_irqrestore(&rtasd_log_lock, s);
+ return -EAGAIN;
+ }
+ }
spin_unlock_irqrestore(&rtasd_log_lock, s);

-
error = wait_event_interruptible(rtas_log_wait, rtas_log_size);
if (error)
- goto out;
+ return error;
+
+ tmp = kmalloc(count, GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;

spin_lock_irqsave(&rtasd_log_lock, s);
offset = rtas_error_log_buffer_max * (rtas_log_start & LOG_NUMBER_MASK);

--
wbr, Vitaly